I don't think muting scammers makes sense.
1. Scammers will just spin up new nostr accounts.
2. You will end up with tens of thousands of muted pubkeys which relays have to store and clients have to handle. Not scalable.
3. Mute lists have low information density. Most of the muted pubkeys will be inactive because of 1.
I would do a trust based model in which a trust score is determined by your and your friends following lists and positive reactions to notes. If the trust score of a user is below a certain threshold the client will not display his content or show it last. The data is already out there, clients just have to use it.
Next release of Nozzle will do it like this. It's a lightweight client which should work on shitty devices so I'm only doing a very basic version of it. I can get more fancy once I port the client to a desktop app.