I think there is a fine line here...
The guys who go for the skin tight look are usually the ones who can't pull if off that well....
But you can't go too loose either - because hell yeah - we all want to show off at least a little bit!! All that hard work in the gym shouldn't go unnoticed!!
on that note though....there's tight and then there's TIGHT!! It's just obvious when a guy is totally showing off.....like he bought the shirt at Baby Gap or something....