I'd ask questions about the boarders-- how long people tend to stay, how well they get along, and whether I could contact a couple of current or past boarders for a reference. You won't get the WHOLE truth, of course, but the way they answer the questions should give you some idea.

There's drama at all barns, but some are able to keep it to a minimum, whereas others almost seem to encourage it. My current barn is anything but fancy, but I love it because the owners don't tolerate a lot of gossip and fighting. Troublemakers and drama queens aren't welcome and don't last long.