1) configurable WOT -> good solution client side
2) If we view relays as a proxy for community with configuration for how exclusive the community maybe that will help concretize the possibilities for relay filtering.
its okay if they aren't an exact community, but framing it that way will help both relay operators and members of the community.
Considering that relays are generally wide open, or wide open after a payment. If good faith users of a relay see something they don't want to see, or goes against the community they want to cultivate they can post a report, or perhaps there is a community voting mechanism for anyone the operator thinks should have stake in the community.
Just to explicitly put it out there, a ban from a relay just means go no on someone else's door with your shit.
You can still say what you want, but not at our house because like it clean.