I think the taste of the can comes from the contact with it. Beer poured into a glass doesn't have the can taste to me but I'd have to have someone swap up a couple of glasses of the same brand from bottle and can at the same time and see if I tasted any difference.
I had a friend who thought my aversion to regular Budweiser was just my imagination for years until I proved it one night. He went to the store and bought a bunch of different singles without me knowing what he bought. They were all on put on ice and allowed to get very cold and during the "test" he poured them into identical glasses and kept up with which one was what. About the 4th or 5th one I kinda gagged and said, "Nasty... that's Budweiser, I'm positive." I knew I was right before he told me because he couldn't keep a straight face after he suggested I should taste the rest to be sure and I told him there was absolutely no reason to because I was right. He said he'd never doubt my taste buds again
