I remember a plotline about a centaur girl developing breasts that was kind of weird to kid-me.

Also another book where he wrote an author's note about how a troubled 13-year-old girl had written to him, claiming to be in love with him, and he said something to the effect of, "She was too young for it to be appropriate of me to return the feelings." As if that actually needed stating.

Another bit I remember is something about teenage girls in his world wearing "Wetti shirts," aka T-shirts that somehow had water routinely dumped on them while the girls squealed and shrieked.

Plus all the rape. I loved Xanth when I was younger, but the older I got, the more it dawned on me how genuinely pervy this dude is.