I find difficulty in taking someone with a beard seriously. Human beings simply do not look or give off the impression of being better in the "fuzzy" sense.
I don't think a beard really decides how serious someone is. However, I do think it makes a guy look older. Or, I suppose, if someone has a beard and they shave it, they look like babies.
I am the same sort who also has a difficult time in taking many hair styles of men seriously, @Carantathraiel. There is a certain attention to detail and disdain I get for it - much of the time I believe because they look so silly. As for women? I never feel one way or the other.
i don't really account hairstyles for much. However, if they walk out with half their head shaved, I sort of automatically assume their brainless trend followers and/or tumblr whiners.
Which is ridiculous, because i've wanted to shave my head for months simply because my hair is a pain in the ass.