Because they are professionals?  What I mean is if I want my house to look amazing, I hire a professional interior decorator.  If I want a fantastic experience in bed, does that happen because I am seeing a professional?  And if so, what do providers do differently or better then say someone you take home from the club?

Well that depends on each Client's Expectations. Everyone's Expectations are different. But as an Overall View, I'd say they're pretty much the same as a Civvie Girl.

Practice makes perfect thats the difference

between pros and civvies. That and the girls you take home from a club are probably sloppy ass drunk and might puke on you and you probably have to take them out for breakfast in the morning and are liable to have become her boyfriend overnight...

Professional or not I think  a "fantastic experience" with a woman requires the following:
1. She is comfortable with her body
2. She stays in the moment, right there with you
3. Here is where it gets tricky, chemistry, either two people have it or they don't and sometimes they have it then it goes away, lastly if you don't have chemistry at first it is possible to attain if points 1 or 2 are evident.
Again professional or not,
and I would imagine the same could be said by women about men...hobbyist or not.

'Professionals' ensure competence and knowledge in whatever area that they are skilled in. It just so happens to be that our profession is in the line of pleasing many which requires quite a bit of practice, attention to what works/doesn't and appreciation of the overall experience.

whether there's an envelope of money left after the fact or not.

You can't guarantee chemistry and that's *really* what it comes down to.

The next question then is how can you test for chemistry before a date is made?  I don't think either party wants to spend time or resources for a situation where chemistry doesn't exist, so how can you establish that before meeting

This is why I love sites like Twitter and such; you can get a feel for someone's personality there. While being attracted to personality alone won't guarantee chemistry (there are many physical factors like scent, physical attraction, body language, and so much more that plays into great chemistry), it certainly can let you know if you're on the right path.  

As far as speaking for MYSELF. One of the main reasons that I am a provider is because I feel that I have talents in this area.  

Jaime,  I'm going to have to test your competitive BJ skills at the orgy party!  With Sage, Amy and Lana there, the competition will be fierce!  

Meet and Greet's are fantastic! I went to my first one, and met Tonja...and boy, was there chemistry!