Paid relays generally get less spam due to increased cost for an attacker
Discussion
Which relay is that?
For example nostr.wine
I am on it though.
If you meant fighting spam proactively - I guess there is no much room for improvement, but I don't think the situation will be worse with the grow of nostr
As nostr gets more popular given the incentives for relay operators, they are the ones who can implement faster moderation due to monetization, which also acts as a fee for an attacker to start an attack
Also I would like to highlight the fact that attacker seem to use only free relays, so at some point of time paid relays can isolate "bad" neighborhood vulnerable to spam attacks