I have never personally owned a rat but my dad breed them off and on for the last 20 years or so. I think as long as you clean them often enough they should be fine. Most of my dad's rats loved to play with eachother on the plastic wheel things, flipping eachother over however some just choose to sleep in them. They were like little tiny dogs! He started out breeding them to have free snake food, but the mothers were so good and sweet that he now feeds frozen food, but he got three as pets a few years ago because he missed them. He has given them all away to friends because of lack of time with a baby, because he also has 6 snakes and two cats. We would take the male, Rocky, and the tame female, Lilly, and put them on our shoulders to sleep curled up in our hair while we watched tv. They were going to buy Rocky a harness to walk him around the house. In all my time with rats, not one has beet me. Hamsters, however, tend to bite a lot more, and mostly out of curiosity.