if you still REALLY want to shop from eBay, take a look at the pictures, if there are any and take a look at where they're coming from. if they're coming from China i wouldn't trust it. most likely it's a bootleg. i've gotten anime from eBay before and they all turned out fine. they were from the USA and Hong Kong (i think). but if you look at the pictures, usually you can tell if it's fake or not. if it's a CD and has Chinese writing on it when it's a Japanese/Korean/English/etc. CD, it's most likely a bootleg.
of course, don't take my word for it. i'm just looking at this from a very small amount of experience.
Jam it back in, in the dark.