Yesterday, when I opened my Messenger's options -> privacy tab, I thought, that maybe you could make Contact List Clean-up more effective by separating contacts into two groups:
1. those, who have you in their contact list
2. the others, who don't.

For example:
contacts who belong to the second group are displayed in different color (i.e. red) and contacts in the first group are displayed regular way. See the attachment...

This is a good idea. I personally never use the contact list clean-up that's in Messenger Plus! though, but if this is possible, it'll be a bit easier then my current method