Depends on the crime. There are some pretty trivial things that can get you marked as a sexual predator.

Statutory rape between people of very similar ages, which usually means a parent got pissed off that their kid was having sex.

Sexual harassment charges for stupid stuff. I knew a guy that got threatened with charges in high school for sticking his tongue out at a girl.

I don't want to protect the actual bad guys but there is a lot of BS that goes on in this area too, much like veterans being put on watch lists or whatever to take their gun rights away.