Why would anyone fake the FFL and then give you a valid DL? It would all be fake if any of it were fake.
Yes, it probably all would be fake. But I think it would be easier to fake an FFL than a DL. After all, penty of guys write bad checks showing real ID, for significant amounts. I think it's partly a case of people caught up in an addition willing to buy something for a $1000 and pawn it for $200 to get a few more hands of poker or lines of coke damn the consequences and partly people who simply realize you can't get blood from a stone. If they are unaware of what extra penalties a fake FFL would bring, I can see someone taking a bit of time and faking one up.