As you said yourself, there is scientific proof that most women have a G-spot. I believe the same. As the girl above said,  I think the women who don't believe they have a G-spot believe so because they simply have no idea where to look for it. :-). Isn't it sad when people don't believe things because they don't know enough information about it. lol.

And about women who don't have orgasms. That is possible. There are women who have conditions that prevent them from achieving orgasm. But I believe that most "healthy" women can achieve orgasm, if not vaginally, then definitely through the clit.

Again, women who are "healthy" (meaning they have no conditions preventing them from doing so) can have an orgasm one way or another. The women who havn't experienced it probably don't know what they are doing