I am strickly keeping my findings to NFL gamers...but I have seen people try and fabricate shoulder pad strap marks on the fronts of the jerseys, but once you have seen a real one, you know what it should look like.

Most people who tend to "doctor" jerseys don't look at the insides of the jerseys, where "wear" is very evident. You can look inside of a jersey and expect to find scuffing, piling, etc. in certain spots.

Repairs are something that you get used to seeing if you're familiar with a certain team, as I am with the Jets. It's easy to spot someone who has tried to fabricate a "team repair", when you compare it to pleny of legitmate samples.

Also there is definitely a different quality/impression that a real NFL hit mark leaves on a jersey, as opposed to people just banging whatever it might be on a jersey in order to leave a "hit mark".

I'm really not going to get too much into specifics, because there are always people looking at this site for the "good", and I'm sure there are some who are looking to perfect their fraudulent craft...and I'd hate to give them any info to help in their deception.