The Baltimore Coin Expo is later this month. Currently, there are 391 dealers on the roster. For a newbie like me, it would be nice to have a dozen or so names that are known to be honest. If there were a website that allowed you to create a "poll" with all vendors them a simple checkbox or radio button, allow you to enter your name, and it would tally/graph the results, would that be a good thing? Or would it be too much work? People wouldn't want to read through the list, etc. Just thinking out loud... Sort of...
What do you mean by "honest?" If you mean, "doesn't knowingly sell fakes," then they're all honest. If you mean, "buys my coins for near retail prices," then none of them are honest. If you mean, "sells their coins for wholesale prices," then again, none of them are honest. Take a redbook, a greysheet, a loupe, & cash with you, ask lots of questions, and be thoughtful about your purchases, and you will do fine.
Sadly it probably won't happen... The show organizers would throw a fit... If people who buy tables from them get NO business because of real (or trumped up) reviews... They will quit buying tables at the show. My advice is just keep your guard up and the honest folks will prove themselves.
When you don't know, how do you find out ? You do so by asking, usually privately, people that you do know and trust.