What Slim said..cloak better.
Your fitness also plays a role. If you have a intimidating musculature people are a lot less likely to fuck with you.
I'm not so sure about the intimidating presence thing. I weigh 215 pounds, granted it's about 16 - 20% body fat, but I don't look that weak by any means. I'm also not that weak by any means. However, some guys have a tendency to try to prove their self to me. I think you really get a grab bag because some guys introduce women to me.
For example, tonight I went out because I had an unexpected gift card that I couldn't use for anything. Right as I'm leaving, the guy who saw me puke early in the night because of some terrible over carbonated beers decided he would help me get laid. He was with some people too. I doubt I was hitting on his group because I was too busy getting hit on, but he was breaking his neck to get me laid.
Him: "What's up man! You're the guy who puked!"
Me: "Yeah, I'm leaving. The gum came in handy."
(I'm just about to exchange information with a woman and then go).
Him: "Dude, you should get out here and dance! All these women want to fuck!"
Me: "I already danced and only like dancing for the sake of dancing."
(Random girl next to me perks up and looks me up and down like a dick on a dick stick).
Him: "Dude, I just randomly dance like an idiot! It's so easy to get pussy! We're going to dance!"'
(He and his group are going onto the dance floor).
Me: "That's good. I'm leaving though."
Him: "Your choice man! It's easy pickin's!"
(You don't even know the half of it bro....you don't even know).