For the most part I don't really have contamination OCD but...

...When I realized how someone I otherwise fancy has a mole in a certain body part (No, it's not the body part you think it is, I just want to prevent TMI), I got overly grossed out and mentally acted like someone with contamination OCD, with all the obsessing and whatnot.

Do you mean you worried that body part's mole could infect you? Or is it more about perfectionism and how the person now seems in some way imperfect or "tainted" to you?

The latter.

Learning to challenge irrational thinking and learning acceptance are very helpful with areas like this because that elusive 100% (something our All-or-nothing thinking is pursuing) just doesn't exist and we need to learn to live with the shades of grey.

These workbooks help with Perfectionism. Look at the CCI workbooks section towards the bottom:

https://psychologytools.com/download...orksheets.html

Something like this again, involving the same person, but involving something about their personality.