Dog urinating and defecating on your site while owners watch

I cant stand that or even worse when the site next to you becomes empty now its a dog walk park. We go to one CG in Mass that we love except for that. I do say something to the people holding the dog. The owners of the cg say it shouldn't happen, but it does all the time. I never go shoeless there and don't go out to gather firewood either, less I step in S**T and not in a good way! Lots of bad etiquette out there with fido.