Are the beaches in Riviera Maya Mexico nude beaches or reg. ones??

Yes, there are nude beaches in Mexico. I wouldn't say being topless in a beach is rude, more like as a woman I'd feel pretty damn uncomfortable in a major touristy beach and there's 50 ugly naco men slobbering over me.
I've heard from my sister who lives in the area that even if you're wearing regular clothes, these local men of low education and culture will whistle and slobber all over you. Imagine having someone like that when you're nude. To each their own I guess. If you come surrounded by some pretty tough looking bodyguards, I bet they'll think twice before personally bothering you too much.

As for nude beaches where the locals won't be acting like 14 year olds that get erections looking at Cosmo magazine, this is probably not a sort of thing major hotels will probably know. You have to ask personally at experienced tourists or people that live in the city who will know best.

There's several nude beaches in Oaxaca where people won't bother you. However, expect these beaches to be at least an hour away from a major big resort city.

I have traveled there quite a bit and have only seen ladies without their tops.Never any other nudity. I believe there is a beach some where in Mexico that is a nude beach.Check with your hotel before booking if it is a problem.

Nudity is illegal in Mexico. It is considered by the locals to be extreemly rude. There are some out of the way coves where it does go on, but VERY secluded.