For me, one important thing is cleanliness from head to toe especially at the y.
Another important thing is their attitude. I recently visited a couple agencies to meet thier line up and the contrast in the attitudes of the ladies is really noticible. One will approach with a smile, perhaps nervous, shake your hand, and just generally try to look and act friendly. Others come out, march up (if they come near you at all), shake your hand (maybe) introduce themselves, with a look, no smile, that seems to say, "I hate this job, and I hate you, drop dead and burn in hell!" Well, that may be an exageration but some of the ladies, in my experience do project body language that seems to say something in that ballpark. I know it must be nerve racking and a real meat market for the ladies so I can understand them feeling like meat, and being shy and nervous, so I don't hold their attitudes against them. But, if they hate this job as some of them obviously do, find another line of work that they can enjoy.
One more. Significant inacurate, dishonest measurements and descriptions in their ads. In inch or two in measurements is fine but if they say they're a 36 and they turn out to be a 46, well that's a different matter. Or if they say they're 25 when they are 35 or older, that's where I draw the line.