I've ruined more shirts than I can count trying to iron them in hotels when the crusty-god-knows-what comes out of the complimentary iron.
Sometimes, you just have to accept the fact that life, and shirts, have wrinkles.
(Seriously. WTF are people doing with these things? Ironing plastic? Cooking ramen noodles?)
Polos? It's going to be moobs on the fatty end and way-too-tight shirts from the body builders. Yuck.