Would most women be willing to have their anus licked by a guy during sex?

Why do you need to know about most women? Surely it's more important to know if the woman you are having sex with is open to this? The only way you'll find out is to ask her. Or tell her gently that this is something that would turn you on, that you wouldn't try to kiss her afterwards if she didn't want you to or any other provisos that she would be allowed to put in place. Be honest with her. And if she says no, then respect that.You do need to understand that everyone has different sexual preferences. If one person may like something there are others that wont. And there is nothing wrong with it.