You may find that an escort who you've enjoyed seeing in the past is suddenly not available when you try to reach her to book an appointment. At first you may just figure she's busy, but when you notice that she repeatedly flakes you off, cancels plans or doesn't answer at all, it's pretty safe to say that she may specifically be avoiding you. This can happen for several reasons, most of which are legitimate and understandable but some of which may not even occur to you at first.
You are always trying to talk her rates down. Most escorts consider this somewhat rude and no one likes customers that are constantly trying to get some sort of discount or deal. If you can't afford her rates, don't pester her and try to talk her into lowering them for you. Why would she answer your calls when there are plenty of other guys willing to pay full price and not blink an eye at it? The best way to remedy this situation is by offering her a tip or letting her know that you have the full amount this time when you send a text, email or call her up on the phone.
You take advantage of her time. This one is fairly common too, especially with ladies who are generous and laid back with their time. Remember, these escorts are the ones you want to keep seeing. They are not glancing at their watches or making you feel rushed. The worst thing you could do when you find one of these ladies is push her limits to see what you can get away with and blatantly take advantage of her time. The best way to fix this is by making it clear that you won't go over the agreed amount of time, or let her know that you're willing to pay extra for extra time spent together.
Your significant other has contacted them. Chances are, if this is the reason that an escort is avoiding you then you already know. Rarely do spouses or boyfriend/girlfriend's spare you of knowing that they have found out about your encounters. This one is more difficult to fix and there isn't any approach I can recommend, as each situation will be drastically different.
You were high or drunk during an encounter with them. Trust me, no one cares for a client who is really intoxicated or high. The effects of both on a person's mood and sex drive are anything but pleasant for an escort. I would recommend apologizing for the last meeting and promising that you will be sober for the next one.
You said something to offend or upset her. Sometimes escorts may have been offended by something you said or did during an encounter, but unless you are a jerk then it's not very likely that she's avoiding you because of something like this. The best way to find out is to simply ask and my advice is just be as polite and respectful as possible when she visits you.
You came across as creepy. This one is tough to tackle, and you may just want to move on and try seeing some new escorts if you have managed to genuinely creep someone out.