My two cents worth:
1. Cleanliness (which, in my mind, translates to clean, fluffy towels and something comfortable on the table--can't stand the sheets of wax paper some places use, you know who you are)
2. Friendliness of the ladies--(SPOILER ALERT: GETTING ON THE SOAPBOX) let's face it, if you've got a ring on, you're there for a reason, or, as Tom Waits put it, "Get'cha a little something you can't get at home..." so the worst thing for me is an interrogation as to why you have to do this when you're already married. I remember someone posting something about Crackers Vs. Ritz. Enough said.
3. Most importantly, which probably means I shouldn't have made this third, is LADIES WHO ENJOY THEIR WORK. Personally, I prefer naturally gifted MPAs, but I have had great experiences with smaller gifted ones who did, or seemed to, enjoy the session (going back to Point 2 above).
4. Last point, I like discrete entrances (which, admittedly, you can't do anything about being in the mall that you're in because I've been past it a few time without going in so I know where you are) particularly those that don't have locked doors that make it seem like forever for someone to answer after you ring the bell. Like I said, don't know if it's the case for you or not but if I did go and encounter this, away I go.
All told, success, in my view, means making sure the MPAs know they're providing an escape and if they treat the customers fairly, they'll (hopefully) be treated in kind.
Andy Rooney checking out.