Everytime I have been to Rios there have been lots of Middle Eastern and Eastern European guys that go around pestering girls. They follow women around and have little to no respect for them. So if your a single girl going there then I would say be very careful and try to stay close to some normal people and couples.
Once I went there was a really nice English girl who had a great curvy body. These guys were following her around everywhere. I was sitting in the hot tub near the saunas watching them follow her from hot tub, to sauna, to steam room and back the hot tub. They weren't even subtle. They would just grab her boobs as if it was their right. No respect what so ever. I moved to the main hot tub near the plunge pool and about 5 mins later she came with them following soon after. She clearly looked miffed but came over and sat near me. I joked loudly and said "your stalkers are back". This sparked up a conversation which apparently was lacking from her fan club. Honestly these idiots think that a way to seduce a woman is just to grope them. She was telling me how they tried to stick their fingers in her pussy without even looking at her. At one point in the conversation, which was going very well, she leant over to whisper in my ear about going to a private room for a massage. At this point one of her ass cheeks lifted up and a guy stuck a finger straight up her ass. Unbelievable. We both got up and left the hot tub, and a few guys tried to follow us. She wanted to go to the changing rooms. I thought she might want to leave but she told me to wait. A minute later she came out with a little bag like a wash bag. She said lets go to a private room so she could give me a massage. So in we went, removed our towels so I could have a pillow and she gave me a massage using the oil from her wash bag. It was great and she gently played with my cock at times. I asked to massage her and that was great too. I played with her pussy and those great tits. She reached in her bag and pulled out a condom. We then had some great sex, twice. Afterwards she said until she met me in the hot tub she would never go back to Rios. The stalkers are a real turn off.
I don't think its really a good place for single women. If they go, they should try interacting more with couples or those that don't follow women around and respect them. A lot of fun can be made with couples that go. I met a Brazillian woman there once with her male friend. That night ended with all 3 of us going in a private room. Plenty of spit roasts and even a DP. I was on the bottom with her on top of me. Great tits in my face while my cock was in her pussy. Her male friend was round the back fucking her ass. It was quality. I didn't have a go on her ass which was a bit of a shame.