Revcollector- I did consider the perfs not being scissor-trimmed as they usually are, but going through the 2c database it looks like there are many that have also been removed by hand. Some are clean, some not clean.

I've never seen a certified special printing in hand, but I do have experience with proof plates and lots of experience with the standard issues and all of the paper varieties they come on. Actually, there are two proof plates submitted as 168s in the PF database you posted, and one can be quick to make that determination without having to look at the description if they have pretty good experience.
This brings up another good point about SPs:
Online images are all over the place in terms of detail, but a proof is always something that can be easily recognizable despite the image quality. Special printings are different. They are somewhere in between a standard issue and a proof in terms of design detail (but closer to a proof).
This means that your assessment has to be correct, in that the stamp will "pop out" at you when you examine it in hand. There's really no other way to explain it in greater detail, and must take experience and knowledge, then instinct.
Pictures of a special printing can actually mislead the collector if that's where they place most of their confidence in, because the range of image quality is so expansive. To add to the confusion, some images even had their resolution enhanced to give the stamp a stronger look, which can also be proven digitally.
I thought about this one, and I don't blame anyone for doing this because, as I've shown in my own images, scanners don't usually do a good job of showing the uniqueness of what can be seen in hand. That must be frustrating for someone that's trying to show others what they themselves see.
Then to add even more chaos, there are certified SPs with printing anomolies like over-inking which causes a darker color and the ink to bleed into the design. I have many over-inked banknotes that do look quite special, but the two I'm showing here have something exceptional about them that makes me at least confident in a submission.
It wasn't the best idea to splatter all of the images separately like I did above, so I tied it together many standard issues that have exceptional detail in hopes of letting you see at least a better version of what I see in hand.

Again, the scanner is way less impressive than what is seen in hand. It is 'sleek' and 'refined' in a way that I haven't seen on any other banknote, but it's hard to put into words.
The three directly above the clipping and the red "paid all" below it are ribbed papers. I included them because ribbed paper is known for having deep and clear printing quality, but the pair still blows them away.


