Paid relays deter spam. If your note is written to a paid relay, some nostriches may see this as higher signal and/or less likelihood of spam than a note coming from a free relay.

When the community hasn't enough volunteers running relays it supports the entire nostr relay network. Filterung can also free relays like nostr.band. somepeoples say that paid relays are not willing to sell ur identity as an free one.

May may not, know oneknows, but i dont think so