Taking Dogs to Outdoor Public Events

The season of farmers' markets and open aire markets is swinging into being here on the Olympic Peninsula. We have farmers' markets in Port Angeles and Port Townsend and an open aire market in Sequim, and this weekend marks the start of the annual Irrigation Festival, a huge deal that goes on for 9 days, with plenty of outdoor activities.
So that got me to thinking. What is the accepted etiquette for bringing dogs to outdoor public events? I encounter plenty of dogs at the farmers' markets and, dog lover that I am notwithstanding, I don't think most of them should be there. Their people generally are paying no attention to them other than to hold onto the leash, and wouldn't know if they peed on a display or pooped in the street, or even bit someone (until the screaming started). The dogs are sometimes okay with it all, but sometimes are overwhelmed by all the activity and totally unsupported by their human, and generally looking for a place to hide. Other times, later in the season, they're wilting in the heat of the street or burning their paws.
I used to bring my dog Nestle to the farmers' market to help socialize him. But all of my attention was focused on him. . . I wasn't shopping or visiting. He was afraid of many things, and I had to be ready to take him away from a situation at a moment's notice, or reward him for relaxing in less trying circumstances. I have a trainer friend who brings her rally dog to the markets to practice amid distractions.
But by and large, the people on the end of the leashes appear to be pretty clueless. I've heard a few vendors complain from time to time (probably after something they were hoping to sell was ruined by a dog), but by and large the public doesn't seem to say much.
I have brought my dogs many times to the open air concerts that take place in both Port Angeles and Sequim during the summer. There, I can choose not to be in the center of the action (or too close to the loudspeakers) and can settle down and relax with the dogs. They seem to have quite a good time. Whether or not the appreciate the music, they like my attention and the occasional pat from a stranger.
I just wish people would give a little more thought to the situations into which they're venturing with dogs. I hate it when other dog owners give the whole group a bad name.