“I work with folks experiencing homelessness. I work with folks experiencing drug use and abuse problems … But still, the No. 1 complaint I get, every day, is dogs off leash.”

Sam Gannon has seen it all, which is another way of saying that he’s a ranger in Denver’s downtown parks.

“I work with folks experiencing homelessness. I work with folks experiencing drug use and abuse problems. Urban camping issues. You name it, I get it down here,” said the affable, bearded young man. “But still, the No. 1 complaint I get, every day, is dogs off leash.”

We were walking Commons Park, where I’d often seen a gang of golden retrievers galloping stupid and free. This is a distinctly Denver issue. People here love dogs, Gannon points out, and they’re increasingly living in apartments and condos without yards for their animals.

It’s worst, Gannon said, in more southerly residential areas, and especially in Cheesman Park, where there are fewer nearby dog parks.

And yet, some of us still find a way to follow the rules. So I wanted to know: What emboldens people to do this stuff? Who do they think they are? And how do we make them stop?

I had already been asking around.

A few months earlier, I’d stood at the very same spot in Commons, watching the insufferable retrievers. There’s a dog park about 500 yards away. Masking my mild contempt, I went to ask “Why?” (Also, I was wearing running shorts.)

I heard a few different responses. One young woman had just moved into one of the apartments near the dog park.

“The dog park’s really nasty. It’s disgusting,” she told me. That’s true. The dog park is full of dog poop because people are really bad at having dogs. Another owner, a 43-year-old man, said that the dog park was full of “really aggressive” dogs that “come in from different areas.”

All the dog owners — probably five in all — had brushed with the parks department at some point or another. They laughed together about “Jane,” who would occasionally spring out from behind trees and ticket them. (They were referring to Jane Broida, a “ranger of the year” award winner, according to the parks department.)

The older guy said he’d gotten “three or four” tickets at $80 a pop. He’s a finance professional, so it seems he could afford it. “The whole ticketing thing kind of seems like a cash grab,” he said. “There’s a lot of illegal stuff that happens in this park and they don’t do anything about it.”

The city could do little to convince him to leash up, he said. “I wouldn’t know an argument against it. It’s for the dogs. They get exercise. They’re not bothering anybody.”

I’ll admit that I wasn’t really bothered at the moment — it’s hard to stay mad at a half-rack of retrievers — but he had used a frustratingly common excuse.

“If they’re not bothering anybody, what’s the big deal?” said Mercedes Devitt, whose dog Bailey walks herself through Wash Park.

The ranger admitted something to me.

As I walked with Gannon, I asked whether he thought he could really change people’s behavior.

It turns out that he’d already changed his own.

“Before I started this job, I’ll be honest, I was one of those folks who let their dogs off-leash in the park,” he said.

I might have gasped.

Gannon said he was conscientious when he did it, waiting until the park was empty. But the complaints that pour into his email inbox have showed him the error in that logic: Sometimes, the park stays empty because people don’t want to be near a bunch of unchained canines, he said.

It can also be a pain for dog lovers. Some on-leash dogs (mine) don’t really like off-leash dogs. It’s not fun when you’re tied up and some huge blond thing wants to play.

So Gannon tries to change people, one leash at a time. The rangers even have a script: Introduce yourself. Tell them to put the dog on a leash. Ask them why they do what they do. (This sounds like my dream.)

“A lot of the folks do it because they think they can get away with it,” he said. “They’re not seeing the impact.”

Ninety percent of people apologize and comply, he estimates. Sometimes you have to fine them. Sometimes you have to bring the police in.

“And some folks just don’t follow the rule at all, because they want to do what they want to do,” he said. As with everything else, it’s pretty difficult to make someone comply with a law once they have the resources to simply pay their way past it, or if they’re willing to simply ignore the justice system.

I suppose Denver could adopt the king of progressive fines that scale up with your income, like they have in Finland. More likely is that the city will just build a few more dog parks. They’re already experimenting with it — our last stop was at Speer Boulevard Park, an out-of-the-way little pocket where the city recently ran a pilot “pop-up” dog park.

The experiment’s over now, but we still spotted a guy and his mutt-terrier-looking dog. Gannon didn’t say anything. He wasn’t bothering anyone.