Yep, really deep water with this one.
A lot of suppliers will send you fake warranties and such, so it's hard to tell from that aspect. I would suggest you look at the brand name of the product, if you don't know it then do some research on it.
A quick Google search could turn up the company name, then you can see who the brand owner actually is.
Bottom line, if it has a brand name you know, then don't even worry about searching, it's a fake or a scam.