I'm more of a "Closet Trainer" myself. I have a few friends who like it as well. I am addicted to the games, but I would never be caught dead in public doing anything Pokemon-related at my age.
Whenever my stepdad walks in, I minimize down the PC Forums, any sprite comics I'm working on, etc. Of course, if you saw a kid minimize a window down as soon as you walked into the room, you'd have a pretty strong assumption on what they were doing. I had no choice but to eventually tell him I have been getting involved with Pokemon, since it's a great alternative to looking like a porn addict.