Thanks for the responses. Has anyone seen fakes of these before? And with these perfs?
The watermark, upon closer examination, appears suspect. Especially because it's white rather than black. These photos are of the 50pf using Clarity. It's hard to see when dry or very wet. I snapped the photos right as the fluid was nearly evaporated. The other 3 are similar.
These stamps have no gum, and I don't think genuine watermarks are supposed to change when the gum is removed. So now my theory is they are indeed forgeries (poor ones because of the perfs being wrong), complete with inky or oily "watermarks" which someone removed after the fact, leaving behind their ghostly remains. Is there any part of my theory which is obviously wrong?