Allright this is going to sound stupid, but the most common mistake you make is by avoiding the clitoris allmost alltogether, just because you think you've reached the promised land, doesn't mean you have, you have got to make visual contact with your target, because just licking the hood is a noble effort, and if you do it for long enough, I'm not going to lie, I want you to think you're doing a good job because I appreciate the try, but it's really just very frustrating to see you trying hard, and really, I don't think anyone wants to tell someone they like and want to see again that although he thinks he's close, he's not even using the right ball..uhm that sounds wrong, hmmm dont use a puck to make a field goal?(Disclaimer: when you hear later the rumor that Nikki told some guy he could only use his left ball to please her, that is not what I meant,and I am not prejudiced against the right ball, somehow singling it out) But seriously, I don't want to hurt someone's feelings, especially if his last 3 Ladies have him more convinced that he is the poonanie-eating-cannibal-King. I'd  rather leave his good sexual self esteem intact, but I grapple often with the "which is better, fake mutiple O's and have him walk away feeling like a champ", and  "maybe you owe it to him to teach him or to society, who the hell else is going to?  God knows the next girlfriend will be delighted with you, and him"  which...wait that kinda doesn't help me very much... uhm nevermind ignore everything I said...
just kidding...
the other mistake is assuming that we all like the same thing, at best it's improbable, at worst it's unconceivable... every clit is different. (why did a Monty Python song come to mind?)I mean I can honestly tell you that I go through stages, all throughout my life I've noticed this from age 12 or so, where everything just gradually changes in terms of sensitivity, and what the guy I was with used to be the , he was THE DATY GOD... the best I've ever had...I'd do a little end zone dance and spike an imaginary air ball!(after the effects of multiples and G-spot combo wore off and I could stand again, of course) Tehn one day it wasn't doing it for me, I couldn't bust even the tiniest one for him. It was like a period where I thought progressively that he was doing something different, which then made me wonder who else he was doing, how could they untrain him like that?? I even accused him of it, then to find out one day while doing myself manually (yes all the time),that the same stuff I'd been doing wasnt cutting it for me,either. Well hell if I can't do it with my own hand, how can I expect someone else to be able to with their tongue no less? I thought something was wrong with me, but then like a couple weeks or maybe 3 passed, and then suddenly everything went back to normal. So It may not always be about whether you're doing a good job or not, because maybe she isn't in that frame of mind, so to speak?  I'll tell you its only happened maybe 3 or 4 times in my life, since I started being orgasmic (age 12... I experimented alot with other girls at summer camp that year)so don't think it happens often,to other women, I haven't ever asked any of my girlfriends if it ever happened to them, but I bet it's pretty likely.
Hope that helped... at all even...  Ladies???? Help!

Kiki,

Would that same communcation go to a provider? Seriously if you had a client that truly wanted honest feedback and wanted to improve in this area, you would work with him rather then fake orgasms??