The point I'm trying to get at is without the point of reference, you wouldn't know how it was on the PS4 and what was actually improved with the Pro for most people since like you said, games will vary in image quality.
I don't think most people would know what to look for and I bet even people who did know what to look for would mistakenly get some wrong.
Hmm.
Of these 4 Ratchet & Clank shots, 1 is from the latest patch, 3 are from before the patch. I've deliberately not picked images that are in the same place. Who can see the difference? Note. These are all just from a PS4, not a Pro.
http://i.imgur.com/q7z84n8.png
http://i.imgur.com/ddGdtS0.png
http://i.imgur.com/Um6gD13.png
http://i.imgur.com/KuY5XuZ.png
Answer:
the third one is post patch.