Yes, 95 % of the time. If the service was not as expected (really bad) then no.

Never expected, always appreciated...

I don't receive tips from everyone, but I definitely always remember the ones who do. Visiting a provider is not like going to a restaurant in which a tip is mandatory, but it does make a guy stand out. Someone who leaves a tip is likely to stay in the provider's mind when it comes to scheduling and perhaps maybe even prioritized in the future. It's like most things though. If you extend extra kindness or generosity to a quality provider, It is likely to be reciprocated in some form or fashion.  
You can't go wrong with a tip. I say if you can afford it,  give a tip to someone who shows you a wonderful time.

i did when i asked her to be my reference  

In terms of a cash tip, my practice has been to give one if the session ran appreciably over the allotted time or if it was well beyond expectations.

Beyond that, I almost never show up empty-handed.  I typically bring some combination of the following:  nice wine, non-alcoholic drinks, snacks, dessert, and/or a gift card.  Some women seem to appreciate those things.  If someone expresses her gratitude, I'll do it again.  If she does not mention the gift, I may eliminate it on the next date.

I also present the donation in a Papyrus gift card.  It's so much classier than a plain white envelope

When I was coming up, you'd go to an AMP for a table shower and "massage" and only get full service for a "tip" which back then was spelled out pretty explicitly what was for what.  Since I haven't been to an AMP in more than a decade and a half I'm not sure if that has changed or not.  Now the classic custom of tipping like you would a waitress, that's tricky.  See I agree that a highly paid provider is a professional and has already put her price point where it needs to be.  Extraordinary service may sometimes get a little extra, but usually it's been rough to gather that much cash to even be there at all, leaving little for altruism.  I've never been a haggler.  I hate auctions.  Tell me a price and that's what I pay usually.  Now if the cost is 350 and all I've got is 20 dollar bills, I'm not going to ask for my $10 change back, that's just rude, but generally the price is the price for me on the first go round.  Now if she is spectacular I might go for a multi hour session the second time I see her (and since I usually only have 2 shots in me, she gets a fairly easy time for most of the 2nd hour.). But for a first visit, probably no tip, just economics...

Whenever we've spent more time together than agreed upon, or when services not originally agreed to have been offered (used to see a sensual massage gal who surprised me being basically FS), or a couple of other special situations, then Yeah, I've tipped.

And Yeah, I often show up with some kind of gift--usually something innocuous like chocolates or something.

But as a general ongoing "thing"?  I can't see it.  I feel sort of like the poster who said that tipping a provider would be like tipping one's dentist.

If the provider becomes more in demand, or wants more time to pursue other things, she's free to raise her rates and not grandfather her existing clients, I guess.

If the gilr works for a house - Yes - it makes up for the cut she has to kick back to the house madam.
Indie - No-she is the owner and gets to keep 100% of her fee. No one ever tips the boss.
Agency girls - depends on the level of the agency and level of the service provided independent of each other - did she go the extra mile, was she jaded and just going through the motions to get you in and out. Did she allow interplay that some might charge an extra fee and finally as in all ladies-did she enjoy herself and allow free expression where it was not a service but a fine encounter.

and it felt so good I was going to cum so quick I just let it go
had no idea there was no condom on jimmy.
shot a huge load inside this 19 year old girl I had never met before.  
I gave her an extra 20.