I'm not sure there's "Fake" IOIs so to say but there's a difference between being friendly and affectionate and throwing you an IOI.

Some girls if they feel they're in no real danger of being hit on or picked up by a certain guy will touch them and tease them in an affectionate way without actually showing any real interest. It's like when that annoying guy is walking your way and looking dead at you. You think to yourself "ah fuck me, I do not want to talk to this guy."

Most of the time you're probably going to be nice and talk to him anyways. Laugh with him if he makes jokes, etc, etc even if they're not really that funny. Online people say what ever they want without remorse but rarely do girls offline tell someone annoying to piss off. For them it's much easier to feign interest or just to be friendly.

Hell, I thought this girl a couple months ago was genuinely interested me, she gave me her (or a) phone number and when I tried to call it, no one ever answered. I waited a while and tried to text but she never responded. Yep.. some girls will actually give you their phone number even though they have no interest in talking to you. All apart of being affectionate and friendly.