People on Nostr are… well… people. I'm working on a solution for this in Haven: a private local ownertrust list where you can indicate your level of trust in a given npub. This covers use cases like: “I want to follow npub1xxx, but I don’t trust them to do proper diligence, so don’t consider their follows in my WoT.”
I also has a ignore list for folks to ignore bots and annoying noub.
I’ve been running this for the past two months or so, and it has been working well for me.