I think for free relays it will be a combination of WoT, machine learning, LLM, and some more manual hardcoded algos. Whoever can do these properly will be ahead of the game. It will be a whack-a-mole for a while until tools are properly installed in relays..
Some relays may share their results as in reporting events for others to use.
Big relays may enforce PoW for a while to be able to accept the initial notes. But users could have another option to just submit to smaller relays and get some history and then big relays if they don't want to do PoW.