How to tell if a guy has a girlfriend

What a predicament.
There is a boy who makes me laugh and I'm considering seeing if there's anything there (we're going to a party and everything). BUT a certain friend of mine tells me that this Funny Guy has a girlfriend.
The question is: how do we know? If you're in the same situation as I am then take note of my 6 ways to know if he has a girlfriend:
1. Check his Facebook Profile. This sounds simple enough, but nowadays guys won't admit they're in a relationship with someone until they've been dating for months. So you could be wasting your time on a guy who's dating someone else but hasn't made it Facebook Official yet. Funny Guy may fall into this category I'm afraid...
2. Ask your friends. If you have mutual friends with the boy then they should know all the gossip.
3. Ask his friends - that is, if you're friends with his friends (otherwise that would be beyond awkward)
4. Browse some of his Facebook pictures - if he has
A. A profile picture with a girl and loads of people comment "awww you guys" or "so cute" then it's probable that they're dating
B. Loads of pictures of days out they've had alone together, then they're probably dating

5. If you and the boy chat a lot then you can ask him (in)directly if he has a girlfriend - i.e. "Do you have a girlfriend? I seem to have forgotten..." or "Valentine's Day sucks when you don't have a boyfriend/girlfriend - right?"

6. WARNING: this method will constitute cocking-up the situation but it is nonetheless effective: get drunk and call/text/ask him in person.

Keep you posted how the party with Funny Guy goes and let's hope, for once, we avoid doing number 6...!
Grammar Gal xxx