I am about to tell you all some deep truths, so listen up.
1) If the guy has both a Three Musketeers facial hair situation and long hair, a la "metalhead gentleman", he is probably bad news.
2) If you think "yeah, there's a good chance that guy owns a utilikilt that he wears to goth/kink/fetish/poly events", he's probably bad news.
3) If you're looking at what to you looks like a really hot mate and you're going "but Rose, this guy seems great, he read me 'My Mistress's Eyes'while wearing his steampunk top hat while we stood on a bridge at sunset"--you can send me a picture and/or let me spend five minutes with him, and I can tell you whether you've found the exception or not.
Listen to me, the Tiresias of nerd culture, having been both a Fake Geek Girl and a Fuckboy. I come bearing tidings of Woe.