Unless you buy from NFLshop.com or the teams proshop, and hey everyone likes a bargain don't they?, you are going to come into contact with the bootleg jersey. Some are obvious and others are so good that even Reebok admit that they can't tell the difference. eBay is a wonderful place for a bargain and so it attracts counterfeiters.
That being said I believe that most of the UK based sellers are not sure of what they are selling. Reebok does not import the Authentic jerseys and so we don't see them in the stores and therefore have no idea what to look for and up until a few months ago I was one of those unknowing fans. In a few short months I have undergone a master-class of jersey collecting and spotting from our American cousins.
I have been caught out by people I trusted and have fake jerseys in my wardrobe which I bought as genuine, but at that ridiculously low price. I don't want to debate the rights and wrongs of counterfeiting products. We all know it's against the law.
So, firstly then.
Price Most Authentic jerseys in retail stores cost $200 to $250 on average. That's £100 to £125 in our money. So can you sell a genuine jersey for £19.50, like some sellers on eBay. Yes if you are clinically insane or so rich that you do it for the love of the sport. The real reason..... fake jersey made somewhere in the far east and bought for £10. Remember if it looks too good then it's got to be just that.
Photo'sHow many close up pictures are there in the listing. An honest seller, even if he/she is not aware that the jersey is a fake, will supply as many pictures of the jersey as the customer wants, hey they are after your money, no? Beware of sellers who only have one far away shot of the jersey and won't email you any more.
NumbersAn authentic range jersey will have one to three layers of tackle twill numbers zig zag stitched onto it. Never one layer tackle twill and then embroidered with the other colours.

These should be almost stiff and almost cardboard like and flat. There could be some bubbling to single numbers, like the Giants or Steelers but mostly it should be flat.
ConstructionA few of the worst fakes are the replica bodies with numbers sewn on, these are easy to spot as the back is longer than the front, known in the trade as the droptail. These also have dazzle material side panels
Others have inferior quality materials and stitching, which is why the seller won't send you a close up picture. Now Reebok also use factories in the far east and South America and their stitching can also leave a bit to be desired. I know for example that the Bears jerseys nearly always have the wrong font on the shoulders. That's Reebok for you.
Authentic jerseys have spandex sidepanels, just like the game jerseys made by Ripon in Berlin, USA ( the Reebok logo is stitched on afterwards on a gamer by Ripon). Fakers know this and put it in so it's only a guide.
PatchesMany fake Reebok jerseys on eBay have patches attached, etc anniversary or captains patches. These patches are not put onto genuine jerseys by Reebok. Some are available to buy on their own and added to the jersey. Mitchel and Ness jerseys do come with patches. The rule of thumb here is be very wary of patched jerseys, unless the seller is trusted or states that the patch has been added after purchase.
Country of origin, tags
Most genuine jerseys are made in El Salvador or Korea, some have been made in China also. Fakers are putting on tags with the correct country of origin so you can't rely on this.
Tag HologramThe hologram on the tag can also give it away as a fake. There are a couple of holograms out there.
1st - the helmet hologram - helmets surrounding the NFL shield. Genuine holograms show different coloured helmets. Fake same colour.
2nd - footballs hologram - There are 2 kinds in 2006 it went to LEATHER color footballs. Then in 2007 the footballs are different colors and it has the AFC and NFC logos in the background. Some sellers like to show the hologram on the fakes. If you see one with a helmet perimeter on a 06-07 jersey...you know it's a wrong un.


Added 23/11/09. This is the current hologram.

Added 24/06/08 - New style tag (right) alongside a fake tag (Left)
Notice that the hologram is the 2005 style and the edges of the tag are not rounded.

Added 23/11/09. These are the latest swing tags, no new jerseys should have the blue rectangular tags now.

Remember to post your eBay item number in the thread if you would like an opinion before bidding.
I hope that you find this guide useful.