It depends entirely on the guy.
Mustaches are a clear no, unless they come accompanied by a full beard.
But really, there are some men who look far more attractive with a beard than without, because it softens their chin, makes it less angled or hides certain imperfections.
On others it accentuates attractive traits.
I mean, some guys just don't look right without a beard.
Other guys though, are way more attractive without beards, or should have at most a stubble.