they only read from their caching relay, its how they can ban spammers outright and get stats on posts, advanced search, etc.
Discussion
But didn't that backfire with ReplyGuy? I adjusted my relays on Nostrudel and Amethyst and he immediately disappeared, but I couldn't get rid of him on theirs. Same with this one crypto spammer. No matter what I do, he shows up on there.
I'm a relay control freak, tho, so maybe I was doing it wrong, or something.