From Bergen, Norway

I don't mean that all beer judging is harmful all the time, but it's definitely the case that an education in beer judging can lead people astray. Michael Jackson once explained how scientifically trained brewers used to attack him for the way he described beers. They would come up to him saying he knew nothing about tasting beer, and that the proper terms for describing flavour were words like sulphury, rancid, solvent like, etc. What did he mean by using terms like spicy, floral, seductive? Did he have no education in tasting? To which Jackson's fantastic reply was "I understand. I will try to do better next time. Do you want me to describe your beer as sulphury, rancid or solvent like?"

The BJCP and similar programs have done a great job in educating beer drinkers about flavour and the causes of the flavours in beer. The problem is that many drinkers have turned around and then applied this knowledge in the wrong way. They taste a beer and go: "I detect the flavour of green apples in this beer. That means there's acetaldehyde in it. Acetaldehyde is a beer flaw, therefore this beer is bad."

That approach is fine if you're judging a home brewing contest where those are the rules. It's misguided, however, if you're picking what beer to drink, or reviewing beers for other drinkers. The world of beer is a varied and wonderful place with such a variety of beer that you can't make simple rules like that. The first beer book I read taught me that beer can have any number of flavours, but sour is the one thing you can always reliably know must be wrong. It didn't take very long for me to realize that this was not right. And so it is with acetaldehyde, dimethylsulfide, and all the others. There are foods that smell so intensely they make people vomit. Yet other people love those same foods with a passion. And now you want to tell me the taste of green apples is always bad? Come on.

Sour turned out not to be a problem

Basically, people have been trained to recognize these flavours in a context where the flavours are presented as problems, and so they have leaped to the conclusion that they are always bad. But it's not that simple. You need to consider the aroma of the beer as a whole, and then think: do the green apples fit in here, or would I enjoy the beer more without them? This is like clothes and colours. It's not that green is always wrong, but sometimes it doesn't fit with the other colours, and only then does it become a problem.

Ultimately, the arbiter between good and bad is: does it work? And even if it doesn't work for you you should be open to the idea that you simply loathe the flavour of green apples, and so nothing with that flavour is ever going to work for you. Which is fair enough, but not necessarily true for everyone else. After all, there are people on this planet who eat green apples because they enjoy them.

So the lesson is: just because you can recognize the chemical and know that it's sometimes a problem, don't automatically assume something must be wrong with the beer. Something may be wrong. Or the butterscotch flavour from the diacetyl might actually make it better. If you assume it's always a problem you're on your way to only making and enjoying the beers like those made by the people who started this whole line of thinking in the first place. That is, the industrial brewers, whose ideal is beer with no flavour at all.

Perfection, industrial brewer-style

Note: I rewrote the start of the third paragraph to avoid confusion. About 20 minutes after first posting.