Once they have verified you, they will be happy to answer this question.  They want to match you with the right provider for you as much as you want that.  And trust me, a women who doesn't do anal prefers not to be asked if she does, it makes them uncomfortable.  I will PM an independent who has the "don't know" for anal, and that is rarely a problem.  The communication always includes an "I hope that you are not offended by the question", because occasionaly one will be otherwise.  But they all rather you ask beforehand than in the bedroom as some do get offended, still see it as taboo.

Greek is my favorite sex, but it is not enough for me amy more that a women offers (tolerates) it.  You will find there are some women who genuinely enjoy anal when done right (let her be in COMPLETE control, everything slow and gentle, be exceedingly tuned in to her emotional state, facial expressions, do not make her be the one to back off, know if the situation calls for it by changes in her demeanor...).  It should become more comfortable for her, NEVER less comfortable as you progress.  If it goes from OK to she looks uncomfortable, don't even put her in the position.  Thank her for the effort and tell her you would like to finish some other way.  It wasn't working out.  

I have two providers who play with their front door and cum during anal and it is just extraordinary, much much more pleasurable than when a women is just..again, tolerating it.  I have also trained two providers on anal when I inquired and they replied "I never have, but I may be willing to try after seeing your size".  There is nothing more erotic than a beautiful women saying she will try for you...that is better even than the sex itself, knowing she will make the effort to satisfy your needs.

I have had anal with my ATF maybe 15 times now.  I stopped during a session this week and moved onto something else because I could tell she was uncomfortable.  It is not like vaginal sex, she can't just turn it off and on as she wishes.  There are days when it just isn't there, so be prepared for that too.  Just because it is on the menu, and even if she is one of those precious few who truly enjoy it, there are days that it just doesn't work.  There is a lot more going on back there than the other hole, a lot of day to day variables.  I have now had three sessions where the women said yes and I stopped because I could see she was struggling.  You cannot be a greedy lover with Greek you, that is just incredibly unfair to her when she is making that effort to satisfy you.  

If you are hobbying in the DC area, PM me.  We Greek lovers have a lot of back-channel communication because we are all looking for the same girls, the ones who enjoy it, because we all enjoy it so much more that way.

And again, agencies never have a problem answering that after you are verified.  You are very likely to see a PSE upcharge of $100-$150, and you are also very likely to hear "YMMV" (your mileage may vary - meaning she will be assessing your trustworthiness, there is a tremendous amount of trust invloved in a women doing this with a stranger that you won't get greedy and hurt her, she will be assessing your size for feasibility and she will be assessing whether she feels OK with it that given day). You might want to put the PSE upcharge in your pocket outside the envelope if you wish, see how it plays out, but I have always just put it in the envelope.  Again, if she at least makes an effort for me that is every bit as good as consummation.  It ain't a science, sometimes it will work and sometimes it won't, but her effort was even greater if she tried and it didn't work.  She deserves to be compensated.

Yep  You hit one of my "hot buttons".

(diatribe off