It's like a cheeky reverse of an ordinary trompe-l'œil and I think it works remarkably well because the subjects are so interesting. My favourite is MR USA below. He looks like the kinda fellow who'd bug the hell out of us English in public places but hey, we're safe because he's 2D, right?
NOT SO MUCH.
Love the dude below trying ever so hard not to look directly at 'it'.
EDIT: I keep looking at the above photo and singing Paul Simon 'You Can Call Me Al'. Imagine him doing a little twirl after his current strut.