One of the worst aspects of this Sketch Scammers business that Bleeding Cool has been covering of late is that innocents gets caught up in the whole scam and start scamming themselves, without realising it. So they trade sketches, such as these fake Fiona Staples sketches, for high value comics. Then they sell those, leaving the dealer to sell the sketches to also innocent purchasers. Who then also may sell them on.
I also understand that Norm Breyfolgle has also been targetted in terms of sketch scams.
Remember, you can find photos of the scammers here, if you want to keep an eye out.