The regular V-Neck (as opposed to the Douchebag Neck as picture throughout the thread) is fine, IMO, both for use under a button up shirt or on a regular tee.
It only becomes douche when it dips down to show your cleavage, IMO. Actually, a regular non-douche V-neck is actually good for guys with round faces because it gives the illusion of a thinner face (even if your face is just round period, and not necessarily fat).