Apparently there are like 500+ checks for your corruption level that all modify how a scene progresses.
The writting was so subtle, I didnt notice until someone asked the same question and got TheObs to respond.
You'll DEFINITELY know it when you character is being EXTREMELY selfish during a scene, caring more about what they are getting out of it, and using whomever is in the scene as just a means to get off, and not a lover.
And nearly all of the optional examples of the above ALSO further increase corruption.
The one I know off of the top of my head is fucking Ryn with a monstrously huge dick
If you dont mind spoilers. The bottom of this wiki page had a FEW of the scenes unlocked by high corruption, as well as sources of it.
https://wiki.smutosaur.us/CoC2/Corruption