A couple of years ago, when we were looking for our Class C we ran into a lot of that. Some people are just flakes and you can't change that. We saw several where the owner was upside down and wanted us to bail them out of their bad decisions. That wasn't going to happen. The best way to deal with these folks is to not deal with them. If they get huffy about legitimate questions or have unrealistic expectations just walk away. I found that generally the ones who don't return calls/emails were likely scammers anyway on CL. The right rig for the right price is out there. Sometimes you have to work hard to find it. By the way, Dealers are no better than Private Party sellers. Their used units are generally dirty, broken and overpriced. The difference is that they will be more pliable on price because typically they didn't overpay for the rig in the first place.