I admit it, I'm a bit anti-social. I'm far from being a people person, especially in RL. In SL, I try to be a bit more friendly, but I still cringe a little when people I never met before IM me out of nowhere. If it's to tell me they love my outfit or wonder where I got this or that, I answer and that's the end of it. I don't mind that kind of IM. On the other end, I hate it when someone (that I don't know) IM's me and simply says "hi" (strangely, it's usually guys who do that) or comment on what I wrote in my profile (ex.: "I'm Canadian too" or "I know who Roger Federer is" or "I speak french too").
I usually reply (I try to not act like a complete savage), but I stay cold. With the "hi" I usually reply "hi..." (the "..." basically standing for "what the heck do you want") and with the random comment on my profile I simply say "oh" or "ok" (which basically mean "I don't give a monkey's butt" [aka "I don't care"]). Of course, some "hi" lead to "Would you like to come to my place to have some fun". I usually feel like hiding when that happens. It's not because I dress my avatar properly (usually not sexy at all, just cute) that it means I seek some sort of attention from the opposite sex. If I dressed for guys, I'd be naked. So, guys, if you read this, don't randomly IM a girl to ask her if she wants to do some... "stuff" with you. Even if she dresses like a slut. Oh and basically don't IM me. I'm not looking and if I could, I'd partnered my inventory (I'm seriously considering renaming my alt "Inventory" and partnering it... but that would be kinda lame... not to mention weird.)
It's probably because of those situation that when I see a guy standing alone and looking like the typical SL macho (overly muscular shape, no prim hair, sleeveless tee if not a wife beater shirt, tattoos and a skin that looks cheap) in a sim where there are no stores (at all or for men) and not necessarily empty (the creepy invite was on a sim where I was far from being the only girl), I feel like running and hiding behind a tree until said macho is out of sight. It's exagerated, I know, but as I said, I'm NOT a people person.
PS: Strangely, I mind less the random IM when I'm on a RP sim... I suppos it's because RP sometimes requires you to send IMs to people you don't know just to check something.