I'm with the OP, and we have had dogs all our lives. Our Golden (RIP Sass Sept 2013), had free run of our home, she learned not to go on any carpets, and we could literally leave a chicken/treat on the floor and tell her NO, go away for a long time, once we did by accident, come back to a pile of drool close by but she'd never touch it. She could hold herself for many many hours (not that we did that to her more than by accident when delayed once or twice in 13 years. When we sat down to eat at the nook table, she'd get up and turn away so she didn't look begging as soon as we put dinners on the plates and folks sat down = association learned. Our Horses even do things by association/command, so I believe most animals can be trained to in turn be enjoyed by all, if the owners are prepared to put in the effort of punish and reward at the front end consistently. For sure dogs can be trained to hold themselves until they reach an acceptable location to pee/poop, it's the owners that can't be bothered to teach them whats right/wrong or acceptable on a consistent basis - bit like some parents with their kids whom as they grow other adults don't want to be near.
We always ask for sites as far away from the non-pet area as possible for this reason and the fact we've stepped in one too many deposits in the past. Alas, bottom line is, it's the irresponsible pet owners that spoil it for the rest, just as is the case with most things in life.
