I don't like the irregularities on my skin or scalp when I have any kind of blemish or sore. So I pick at them, but I love when it bleeds. Then they don't heal like they should. hmmm...I also despise body hair. Pretty f#@%ing twisted, huh? I used to cut when I was a teenager, but it drew too much attention so I quit. I might take it up again.
I hit a rough spot last year and began doing what you are describing with my scalp. Like you, it was the irregularities that kept me at it.
My doc said it was a form of OCD, which makes sense to me. I also have some trichotillomania going on with it. The scab picking and blemish popping often is associated as well. When I was younger, I couldn't leave zits alone either, and now it is the same way with fever blisters.
My suggestion about the scalp scratching is to try to find someway to control it. Easier said than done, I know, but I ended up with impetigo that is still not under control after 6 months. So this is something that can cause medical problems as well.
There are some suggestions for trich control in that forum on this site or I can give you a few that have helped me to some degree.