"I have to go to China." I told people this in the way I might say, "I need to insulate my crawl space" or, "I've got to get these moles looked at." That's the way it felt, though. Like a chore. What initially put me off was the food. I'll eat it if the alternative means starving, but I've never looked forward to it, not even when it seemed exotic to me.

I was in my early 20s when a Chinese restaurant opened in Raleigh, North Carolina. It was in a new building, designed to look vaguely templish, and my mother couldn't get enough of it. "What do you say we go oriental!"

I think she liked that the food was beyond her range. Anyone could imitate the twice-baked potatoes at the Peddler, or turn out a veal parmesan like the Villa Capri's, but there was no way a non-Chinese person could make moo shu pork, regardless of his or her training. "And the egg rolls," she'd say. "Can you imagine!"

The restaurant didn't have a liquor licence, but they allowed you to brown bag. Thus we'd arrive with our jug of hearty burgundy. I always got my mother to order for me, but when the kung pao chicken was brought to the table, I never perked up the way I did at the steak house or the Villa Capri. And it wasn't just Raleigh's Chinese food. I was equally uninterested in Chicago and, later, New York, cities with actual China Towns.

Everyone swore that the food in Beijing and Chengdu would be different from what I'd had in the US. "It's more real," they said, meaning, it turned out, that I could dislike it more authentically.

I think it hurt that, before landing in China, Hugh and I spent a week in Tokyo, where the food was, as always, sublime, everything so delicate and carefully presented. With meals I drank tea, which leads me to another great thing about Japan – its bathrooms. When I was younger they wouldn't have mattered so much. Then I hit 50 and found that I had to pee all the time. In Tokyo, every subway station has a free public men's room. The floors and counters are aggressively clean and beside each urinal is a hook for hanging your umbrella.

This was what I had grown accustomed to when we flew from Narita to Beijing International, where the first thing one notices is what sounds like a milk steamer, the sort a cafe uses when making lattes and cappuccinos. "That's odd," you think. "There's a coffee bar on the elevator to the parking deck?" What you're hearing, that incessant guttural hiss, is the sound of one person, and then another, dredging up phlegm, seemingly from the depths of his or her soul. At first you look over, wondering, "Where are you going to put that?" A better question, you soon realise, is, "Where aren't you going to put it?"

I saw wads of phlegm glistening like freshly shucked oysters on staircases and escalators. I saw them frozen into slicks on the sidewalk and oozing down the sides of walls. It often seemed that if people weren't spitting, they were coughing without covering their mouths, or shooting wads of snot out of their noses. This was done by plugging one nostril and using the other as a blowhole. "We Chinese think it's best just to get it out," a woman told me over dinner one night. She said that, in her opinion, it's disgusting that a westerner would use a handkerchief and then put it back into his pocket.

"Well, it's not for sentimental reasons," I told her. "We don't hold on to our snot for ever. The handkerchief's mainly a sanitary consideration."

Another thing one notices in China is the turds. "Oh please," you're probably thinking. "Must you?"

To this I answer, "Yes, I must", for if they didn't affect the food itself, they affected the way I thought about it. In Tokyo, I once saw a dog pee on the sidewalk. Then its owner reached into a bag, pulled out a bottle of water and rinsed the urine off the pavement. As for dog faeces, I never saw any trace of them. In Beijing, you see an overwhelming amount of shit. Some of it can be blamed on pets, but a lot of it comes from people. Chinese babies do without diapers, wearing instead these strange little pants with a slit in the rear. When a child has to go, its parents direct it towards the kerb or, if they're indoors, to a spot they think of as "kerby". "Last month I saw a kid shit in the produce aisle of our Chengdu Walmart," a young woman named Bridget told me.

This was the seventh day of my visit and so desensitised was I that my first response was, "You have a Walmart?"

There are the wild outdoor turds of China, and then there are the ones you see in the public bathrooms, most of which feature those squat-style toilets, holes, basically, level with the floor. And these bathrooms, my God. The sorriest American gas station cannot begin to match one of these things.

In the men's room of a Beijing subway station, I watched a man walk past the urinal, lift his three-year-old son into the air and instruct him to pee into the sink – the one we were supposed to wash our hands in.

My trip reminded me that we are all just animals, that stuff comes out of every hole we have, no matter where we live or how much money we've got. On some level we all know this and manage, quite pleasantly, to shove it towards the back of our minds. In China, it's brought to the front, and nailed there. The supermarket cashier holds out your change and you take it thinking, "This woman squats and spits on the floor while shitting and blowing snot out of her nose." You think it of the cab driver, of the ticket taker and, finally, of the people who are cooking and serving your dinner. Which brings me back to food.

If someone added a pinch of human faeces to my scrambled eggs, I may not be able to detect it but I would most likely realise that these particular eggs taste different from the ones I had yesterday. That's with something familiar, though. And there wasn't a lot of familiar in China. No pork lo mein or kung pao chicken, and definitely no egg rolls. On our first night in Chengdu, we joined a group of four for dinner – one Chinese woman and three westerners. The restaurant was not fancy, but it was obviously popular. Built into our table was a simmering cauldron of broth, into which we were to add side dishes and cook them until they were done. "I've taken the liberty of ordering us some tofu, some mushrooms and some duck tongues," said the western woman sitting across from me. "Do you trust me to keep ordering, or is there anything in particular you might like?"

I looked at her thinking, "You whore!" Catherine was English and had lived in China for close to 20 years. I figured the duck tongues were a sort of test, so I made it a point to look unfazed. Excited even.

When I was eventually forced to eat one, I found that it actually wasn't so bad. The only disconcerting part was the shape, particularly the base, from which dangled tentacle-like roots. This reminded one that the tongues had not been cut off but, rather, yanked out, possibly with pliers. Of course the duck was probably dead by then, wasn't it? It's not as if they'd jerk out the tongue and then let it go, traumatised and quackless but otherwise whole.

It was while eating my second duck tongue that the man at the next table hacked up a loud wad of phlegm and spat it on to the floor. "I think I'm done," I said.

The following morning, and with a different group, Hugh and I took a drive to the mountain where tea originally came from. It was late January, and the two-hour trip took us past countless factories. Mustard-coloured smoke drifted into the sky and the rivers we passed ran thick with waste and rubbish. Eventually we hit snow, which improved things visually but made it harder to move about. By the time we headed back down the mountain, it was almost three. Most restaurants had quit serving lunch, so we stopped at what's called a Farming Family Happiness. This is a farmhouse where, if they're in the mood, the people who live there will cook and serve you a meal.

One of the members of our party was a native of Chengdu, and of the five Americans, everyone but Hugh and I spoke Mandarin. Thus we hung back as they negotiated with the farm wife, who was square-faced and pretty and wore her hair cut into bangs. We ate in what was normally the mah jong parlour, a large room overlooking the family's tea field. Against one wall were two televisions, each tuned to a different channel and loudly playing to no one. On the other wall was a sanitation grade – C – and the service grade, which was a smiley face with the smile turned upside down.

As far as I know there wasn't a menu. Rather, the family worked at their convenience, with whatever was handy or in season. There was a rooster parading around the backyard and then there just wasn't. After the cook had slit its throat, he used it as the base for five separate dishes, one of which was a dreary soup with two feet, like inverted salad tongs, sticking out of it. Nothing else was nearly as recognisable.

I'm used to standard butchering: here's the leg, the breast, etc. At the Farming Family Happiness, rather than being carved, the rooster was senselessly hacked, as if by a blind person, a really angry one with a thing against birds. Portions were reduced to shards, mostly bone, with maybe a scrap of meat attached. These were then combined with cabbage and some kind of hot sauce.

Another dish was made entirely of organs, which again had been hacked beyond recognition. The heart was there, the lungs, probably the comb and intestines as well. I don't know why this so disgusted me. If I was a vegetarian, OK, but if you're a meat eater, why draw these arbitrary lines? "I'll eat the thing that filters out toxins but not the thing that sits on top of the head, doing nothing?" And why agree to eat this animal and not that one?

I remember reading a few years ago about a restaurant in the Guangdong province that was picketed and shut down because it served cat. The place was called The Fangji Cat Meatball Restaurant, which isn't exactly hiding anything. Go to Fangji and you pretty much know what you're getting. My objection to cat meatballs is not that I have owned several cats, and loved them, but that I try not to eat things that eat meat. Like most westerners I tend towards herbivores, and things that like grain: cows, chickens, sheep, etc. Pigs eat meat – a pig would happily eat a human – but most of the pork we're privy to was raised on corn or horrible chemicals rather than other pigs and dead people.

There are distinctions among the grazing animal eaters as well. People who like lamb and beef, at least in north America, tend to draw the line at horse, which in my opinion is delicious. The best I've had was served at a restaurant in Antwerp, a former stable called, cleverly enough, The Stable. Hugh was right there with me, and though he ate the same thing I did, he practically wept when someone in China mentioned eating sea horses. "Oh, those poor things," he said. "How could you?"

I went, "Huh?"

It's like eating poultry but taking a moral stand against those chocolate chicks they sell at Easter. "A sea horse is not related to an actual horse," I said. "They're fish, and you eat fish all the time. Are you objecting to this one because of its shape?"

He said he couldn't eat sea horses because they were friendly and never did anyone any harm, this as opposed to those devious, bloodthirsty lambs whose legs we so regularly roast with rosemary and new potatoes.

The dishes we had at the Farming Family Happiness were meant to be shared, and as the pretty woman with the broad face brought them to the table, the man across from me beamed and reached for his chopsticks. "You know," he said, "this country might have its ups and downs but it is virtually impossible to get a bad meal here."

I didn't say anything.

Another of the dishes that day consisted of rooster blood. I'd thought it would be liquid, like V8 juice, but when cooked it coagulated into little pads that had the consistency of tofu. "Not bad," said the girl seated beside me, and I watched as she slid one into her mouth. Jill was American, a Peace Corps volunteer who'd come to Chengdu to teach English. "In Thailand last year? I ate dog face," she told me.

"Just the face?"

"Well, head and face." She was in a small village, part of a team returning abducted girls to their parents. To show their gratitude, the locals prepared a feast. Dog was considered good eating. The head was supposedly the best part, and rather than offend her hosts, Jill ate it.

This, for many, is flat-out evil but the rest of the world isn't like America, where it's become virtually impossible to throw a dinner party. One person doesn't eat meat, while another is lactose intolerant, or can't digest wheat. You have vegetarians who eat fish and others who won't touch it. Then there are vegans, macrobiotics and a new group, flexitarians, who eat meat if not too many people are watching. Take that into consideration and it's actually rather refreshing that a 22-year-old from the suburbs of Detroit will pick up her chopsticks and at least try the shar pei.

I'd like to be more like Jill, but in China something kept holding me back. In clean, sophisticated Japan the rooster blood, arranged upon a handmade plate between the perfect, tempura snow pea and a radish carved to look like a first trimester foetus, would have seemed a fine idea. "We ought to try making this at home," I'd have said to Hugh. Here, though, I thought of the sanitation grade, and of the rooster, pecking maggots out of human faeces before being killed. Most of the restaurants in China to me smelled dirty, though what I was smelling was likely some unfamiliar ingredient, and I was allowing the things I'd seen earlier in the day – the spitting and snot blowing, etc – to fill in the blanks.

Then again, maybe not.

While on our trip we ate at normal, everyday places, and sometimes bought food on the street. Our only expensive meal was in Beijing, where we went alone to a fancy restaurant recommended by an acquaintance. The place was located in an old warehouse and had been lavishly decorated. There was a wine expert and someone whose job it was to drop by every three minutes and refill your water glass. We had the Peking duck, which was expertly carved rather than hacked and was served with little pancakes. Towards the end of the meal, I stepped into the men's room to pee and there, disintegrating in the western-style toilet, was an unflushed turd, a little reminder saying, "See, you're still in China!"

Back at the table I asked for the bill. Then I remembered where I was and amended it to "the check". In France, you can die waiting to pay for your meal, which is something I've never understood. "How can they not want me out of here?" I'll think. Ten minutes might pass. Then 20, me watching as the waiter does everything but accept my goddamn money.

I'll say that for China, though – offer to pay and before you can stab a rooster with a rusty screwdriver someone has taken you up on it. I think they want to catch you before you get sick, but whatever the reason, within minutes you're back on the street, searching the blighted horizon and wondering where your next meal might be coming from.