I've never actually met someone who lies(lied) about being sponsored. At least not by a "big name" company. I don't see how people think you can get away with that. They're a big company. If someone is legit, like you can find that out so easily. Only an idiot would try to lie about that.
Anyways, I met a girl who said she was sponsored for skateboarding locally and a shop was trying to get a girls team together(through her). The girl didn't even know what an Ollie was, but she was "sponsored." Seemed legit? Those kind of people are just insecure or overconfident and think they're good enough to say they have a sponsor. Whatever, just let them do them.