There is nothing really wrong with that. It is possible to clean out your ass before getting fucked there so ass to mouth is no different than sucking dick from a pussy.
These woman are fantastic they are trained to the highest standards to pleasure there man must have been broken in very early and continuously used. Must have been a hard job by there master to have gotten them all to this level. Keep up the good work I've only managed to break in three young woman ever my last one took almost a year, hard work had to give her the belt when not respectful to my orders.