Obviously you would tip for exceptional service.  But what if the service is just OK?  Just interested in others' tipping guidelines.  

For example, if performance is a TER 8-10, tip X.  If TER performance is 5-7, no tip.  Or maybe you never tip at all.

Does the fact if the provider is independent or with an agency factor into your tip.

Interested in hearing your experiences.

I always tip, but with the one exception of where a provider had a bad attitude (e.g. acting totally disinterested) or misrepresented herself (says she a total GFE and won't even kiss or let you touch her). If she gives it the old college try, I always tip, and always leave with a smile and kind words.

For me, tipping is an exception not a rule. I feel that the base rates providers get are already more than generous.

However I will tip when she's truly gone the extra mile to make my session a good one. For example, if she we go a fair amount of time beyond the hour, or when then that second pop choses to be a stubborn son of a gun and instead of throwing in the towel she turns it up a notch so I leave a happy camper.  Also, if the lady has a discounted price structure on a 2 hour type appt, I'd be more inclined to tip in that situation.