The red wire says a number of things depending upon where it comes from and where it goes. It could be part of a 3-way switch setup, a switched receptacle, a combined circuit with a shared neutral among other things. But I have to disagree with Steve that a red wire tells someone of the presence of a 2 way switch in a room because a 2 way switch is a standard switch which only needs a black, white, and ground and not an additional hot/red wire. Start touching hot wires together and start being prepared to meet your maker when they arc. Breakers don't always work and sometimes when it is too late. I think there is a real problem until you understand your wiring.