This is an interesting idea and concept but I don’t personally feel that the amount of contentious bootleg merchandise out there would really justify listing every official item that has ever been released.
There’s some good points of reference for you in what @STORMS has put together on this forum with historic screenshots of merchandise available from afireinside.net. You could also use Discogs specifically for music etc. and Dereks Instagram is also awesome and something I regularly refer to.
Failing that if there’s something in particular that your unsure of then just post it on here or message another person that has that specific item. I’ve had loads of people message me on Instagram to check tags on shirts against my own collection to make sure the item they are looking at is genuine and would be happy to do so for anyone else. If you can find someone else that has the same item you’re looking at buying, preferably that bought it new and the labels match then you know you’re ok.
The problem with listing everything is that even with collectors that have so much (myself and many others on this forum included) it’s probably just a drop in the ocean on everything that has ever been released with every album/ep release and different merchandise available on each tour.
As @Hammonds said if it looks suspicious then just avoid it. From experience anything coming from Russian Federation or Asia that has every size available on an older design is clearly dodgy!
Unfortunately you can’t stop people from listing bootleg merchandise and a lot of us myself included probably still buy it where either AFI don’t make the that specific item or if it’s a old shirt design where the original goes for hundreds of dollars and your happy just to have a reprint.
My Instagram is AFI-Nick if you want me to check anything.