It's one of my favourite things to do (though I wouldn't want to do it for a job...). I've been going to untutored life drawing sessions once a week for about 3 years now, and I've learned a few things:
1. The phrase "Use it or lose it" is absolutely true when it comes to life drawing. If I miss one or more weeks, my drawing ability will have deteriorated noticeably by the time I'm back in the life room.
2. Beautiful people don't necessarily make the best life models. What makes a model a good one is - the ability to hold poses, especially standing ones; interesting face; "landmarks" i.e. muscles, bulgy bits, boobs...etc
3. People who do life drawing tend to be art students, artists and those who wannbe either. Most of 'em are introverted.
I never noticed pervy types at these sessions, though I've been told one or two have turned up and been turfed out.
While I've almost given up on painting due to lack of leisure time, and don't actually bother drawing anything else, life drawing manages to hold my interest even after all this time.
That'll all change when I start my MLIS this year, and have to find 10 hours each week to study in (that's 10 hrs per paper).....