What exactly is the moral/ethical problem with a professional athlete taking performance enhancing drugs? I'm talking about a talented professional who carefully weighs the known risks and side effects of such drugs and decides their use is necessary for him/her in order to be competitive in their sport. Shouldn't this just be a personal decision? Aspiring beauty queens are allowed to get plastic surgery, and athletes are allowed to get "corrective" laser eye surgery (significantly improving their perfectly normal distance vision)...

Loyalty. Is it unethical to move loyalty to another sports team just because the current team you're rooting for isn't doing well?