I've been a victim of clear counterfeit products on two occasions. Ralph Lauren, Fred Perry and Lacoste or the most likely brands that are sold as fakes.
My advice - If the product is priced significantly lower than the rrp price - AVOID. Yes we all love a bargain, but is it worth being sold what is actually a useless item?
If there is any negative feedback with accusations - AVOID. If there is someone making an accusation it is likely to be true. It is harder and harder to spot a fake, so some people may still think they're getting an absolute bargain.
If the seller is based in an eastern country (no racism or predjudice intended) - AVOID.
I've been ripped off to the tune of about £60 on ebay, don 't let it happen to you.
If you want bargains, head to outlet stores or buy from GENUINE ebayers that are not trying to rip you off.