Its potentially cool if they are actually vintage. The AC/DC or Beatles or Pink Floyd shirts you can buy at Kmart that are "vintage" that every single middle school boy has/had are not cool.
Only t-shirt I have that I'd consider vintage is one my dad had when he was in the Marines. Its yellow & says "the Marine Corps: the strong arm of the American Armed Forces" and shows a ripped guy in a Marines tshirt arm wrestling guys from all the other branches at the same time.