There are few things that I get Monkish about, but facial hair is among them. An unsymmetrical goatee or neckline is absolutely unacceptable. Don't even talk to me about it.
Don't pretend that you don't know what I'm talking about, either. I recently screwed up, dinking around with a cheek-line (inadvisable and unnecessary for most of us), and by the time I tried correcting it, the inevitable was obvious: it was time to start over. I shaved. Fascinatingly, about 4 different guys who beheld the nakedness of my face the next day said, "ah, a tragic trimming accident?" They knew! All guys know.
Goatees are among the toughest. I mean, you've got to keep both sides perfectly parallel. If one turns an awkward angle, the other must be made to mirror it precisely. Or what about the angle at which the sides turn under the chin? Getting those to match is well-nigh impossible. For these and other reasons, I don't even bother with goats anymore.
Necklines can be almost as tough. If one side moves up toward the back of the jaw at a steeper angle than the other... I'll lose sleep.
Cheeklines are even more visible than necklines...I advise against them, except for picking off the occasional renegade making a break for the eye socket.
So, next time your wife asks you what the heck you're doing for so long in the bathroom, ask her if she'd like you to look like this guy, or this guy, or these guys.