This reader question came to PC Magazine's Robert Heron:
"My question is about my 50-inch Vizio plasma 720p HDTV. I just got an Xbox 360 and have been playing it a lot. The other night I spent about an hour and a half playing Uno on Xbox live (no cracks about the card game please). Anyhow when I got up the next morning and switched on my set I could see the Uno cards from the game still there, faintly. I ran VIZIO's image cleaner, and it went away. How long can I safely play games on my set before I permanently ruin it? Other games, like COD4, haven't had the same effect, but the slower ones worry me."
See Robert's answer after the jump.