My observations:
1) You can tell a lot face to face. Many people can't keep their inner psycho hidden face to face. Heck, many can't keep it hidden online or on the phone. However, some of the psychos can hide their inner psycho, so don't put too much faith in that.
It's a lot easier to get rid of the guy or gal at the social than when he shows up for an appointment.
2) There's no photoshop, old photos, or clever poses at the social to hide your real appearance. You see a lot more of the real person.
3) A lot of the ladies hang out together and don't circulate. Ladies, you might circulate more if you're wanting to generate business. Of course, if you just want to socialize with one or two guys or ladies, that's OK, too.
4) Don't forget it's a social, not an orgy. No lady or guy should feel pressured to do more than chat, or perhaps exchange handles and phone numbers.
5) Don't forget there's risk of being spotted by a civilian or a bad hobbyist or provider. Don't ever forget there is always risk in the hobby in any activity.
People have occasionally spotted a real world acquaintance in the venue. "Mom, what are you doing here and why are you dressed like that?"
6) It's not about getting an appointment right then and there. Just because you don't make an appointment right then doesn't mean it doesn't get you an appointment later.