Quest, Lava Life and such are very much a hit and miss wrt quality.
I'll give you some personal experiences:
1) "Karen" on LL three weeks ago - , advertises as looking for a "Discreet encounter" with a 39-52 year old man. Says she's 34 , 5'7", 130 lbs and red hair. When you arrive at her place ( it's a City Living building - that should set off alarm bells ) she says she needs money for the babysitter and asks for $40. She matches her description and is cute to boot so ( idiot that I am ) I ride up to her floor in the elevator and give her the $40 as we get out - she says wait one minute and go ahead into apt xxx while she pays the sitter.
Needless to say, apt xxx is locked, nobody home and she has vanished with the $40 - lesson learned.
2) "Karen" - on Quest ( 5 years ago ) - thin brunette about 25-30, cute. A wonderful experience - bbbj, daty( you'd just about drown ), positions. $120 - no time limit . Saw her about once a month for about 6 months until she left the city.
3) "Smokin Hot Blonde" on LL. Looks 3/5, attitude 5/5, service 5/5. Skinny short blonde late 20's - 5'2", 100 lbs. bbbjtc, and I'd have to say that she'd be in the top 5 lifetime as far as BJs go. FS was available but after the BJ I was done.
4) "Vera" on LL - ad says she's 42, 140lbs. She sounded interesting in the messages we sent back and forth and since 42 is close to my vintage I figured that I'd take a chance. Arrive at her place - a City Living building. Get to her door and when the door opens I'm greeted by something that looks like Mr Magoo in drag. I say - no thanks, give her $40 for her trouble and make a quick exit.
5) "Sue" off quest a few years ago. Blonde, 5'8" 135 but had recently lost a lot ( I mean A LOT, she had a picture ) of weight - she was very saggy in places. This lady was a certifiable nympho - BBBJ, positions, daty,msog for me, mmmsog for her - she couldn't get enough after my jaw was too tired to continue she said "wanna see something" and proceeded to bring herself off and squirt. She was kinda like a wild roller coaster ride - fun but scary. Technically speaking I'm not sure she'd be a SP - all she wanted was cab fare to and from her place $50.
6) "Linda" off quest 2 year ago. 30's, pixie-ish face skinny Redhead about 5'9" and 110 lbs. Arrive at her place and am escorted to her basement apartment - and her aparment is messier than mine. I then notice her gear sitting on top of a dresser. I make an excuse, give her $40 for her trouble and beat a hasty retreat.
Long and the short - SPs off of the phone lines may have a better price point and you may find an occasional gem, but for the most part for predictable quality you're better off paying for a professional.
Cheers,
Molari