Yes they are "picky" if you are selling. But really it just depends on how full their racks are, the season, what is selling (Cool jewerly, shoes are hot items). If you are buying, you can't beat their deals on great stuff. Designer, Anthropologie brands, JCrew, Banana Republic...cool stuff. Definitely worth stopping and browsing!
PS Don't act rude or impolite if they don't buy your stuff...too many times I've seen would-be-sellers throw fits and get attitudes. Geesh, act out and you look like a jerk. Instead smile (even if you are irked)and ask what they are buying at the moment. They will appreciate it and maybe go home and raid your closets for the "hot" item of the moment.