... for the love of everything beautiful, I still cannot figure out what is acceptable and what is not. Where to really draw the line between sexy and derogatory. Which means, I refrain from dirty talk all together

Depends upon the lady and how many times you have seen her and comfort level... I would not do it in any emails (like GaGambler said why)- phone may be ok with her (maybe)...

Best to ask in person.  I personally will not answer those questions no matter what over the phone or on emails.  I do take requests in person... or VAGUE requests over phone if I know you.  I do not do dirty talk over the phone or emails no matter who you are- I am not a freebie  It also lacks manners and respect in my book.  

Just because I have seen someone previously does not mean that they are safe... how do I know you did not get busted with some other provider or LE and now doing a setup on me to save your butt?  I am always going to cover myself even if it probably will never happen to me.  I do not take chances.  

I have a client who told me years ago that he had seen a provider a good 30 times and thought it was safe- only to have her set him up to save her own skin.  This was a very well reputable lady.  It rarely happens but it can.  Of course she is pretty well blacklisted in my area now and had to find a new career (or could be still trying on CL lol)  And as someone had recently mentioned within the past few weeks... another provider in my area turned on her clients.  It's all over H&H concerning it.  

If I ever have that happen I will take the stupid ticket and go on with my business.

It can be exciting if both parties are into it...but there's a big difference between:

"I was turned-on the moment I laid eyes on you.  You were aggressive yet slow and easy, a perfect combination.  Your kisses were like heaven.  When you pulled your top down revealing your magnificent breasts, I couldn't keep my mouth off them.  Then you sat in my lap and the kissing and rubbing got serious.  It was so exciting to be doing this with you in broad daylight, that's why the thought of skinny-dipping turns me on."

and

"I wanna bang you in the ass! I'm gonna make you take all this cock, in every hole of your body. Deep in your pussy and then I'll take it out and make you suck all the hot juice off me and then ram it in your..."

You get the idea

The first example is more acceptable if you've just met and testing the waters...

The second example, you have to both really be into each other(and all the items discussed are on the menu!)or it's like a porn movie, the dialogue is annoying, ff to the action already!

fwiw
xxx