Okay, this was a topic of heated debate and I'd love to get a wider perspective. I'd have put it in "Guy Talk" but I think that women likely have a serious opinion as well.
In my circle of (mostly) American male and female friends, the majority of us agreed that under most button-down shirts (and for some of us - under everything except T-shirts) men should wear a full white undershirt. That this article was as necessary as a bra for women, and served a number of functions, including wicking away underarm sweat and lengthening the lifespan of shirts, sweaters, etc.
Tank-type undershirts (so-called wife-beaters) were considered weird, but apparently the preference of one of the hairier males. Some of us thought that this defeated the whole purpose of the undershirt, but at least it did cover some of the creepy chest hair.
A single male thought that any undershirt was unnecessary and never wore them. He proclaimed he did not sweat that heavily and simply washed his shirts after each and every time he wore them. He also had IMHO gross chest hair creep (at the collar and through the gaps between the buttons) and when it was suggested that he could get that situation under control with an undershirt, he proclaimed the hair as "masculine"
Now, I would never have thought to make a UK/Europe - US distinction here, except for the fact that I recently saw the HUGO cologne commercial with John Rhys Meyers (or whatever his name is,.. the one who plays King Henry VIII in "The Tudors"). He's wearing a thin white button down shirt in the commercial - virtually see-through - and no undershirt. My reaction was totally "eeeew" but then I wondered if in fact this was a cultural thing.
So - ladies and gents, if I knew how to create a poll the questions would be:
Full t-shirt undershirts for men:
A. Necessary and desirable
B. Weird
Thoughts? Opinions?