Seems like more spam is coming to nostr lately
Discussion
Paid relays fix this.
More spam solutions will be coming to nostr too. Here are a few:
paid relays - if you only read from paid relays, and they work at removing spam somehow.
filter scripts - if you can think of a way to characterize notes you don't want (e.g. says "AirDrop") scripts in clients can drop these notes. Gossip is close to having this.
PoW - IMHO not a good solution as spammers can PoW just like everybody else can.
social distance - If the person is not followed by someone you follow, don't show those notes
classifying people into more buckets - if clients allow users to mark a person as "recognized but not followed", then this can grow their social graph by a lot, and the social distance algorithm won't prune out quite so many people. I intend with gossip to have a thumbs-up/thumbs-down button on people you don't follow so you can "recognize" that they are a regular person not a spambot, without following them.
What about muting any user who is nip-51 muted by your follows? (Or maybe needs to be muted by 2 or more follows, or some percentage of your follows). Seems like a lot of bots would disappear pretty quickly that way.
Good idea. But yeah, I would want two or three follows muting first.
Maybe let users view the curated mute list the way the relays list is viewed below, and then select the threshold number of mutings before you auto mute. Would be interesting to see how many profiles get muted by lots of follows vs muted by just one or two.
Maybe also include follows’ follows. 
id make a bet all the instant-reply airdrop spam and ‘ab289sdd8’ spam would die if PoW relays got used for threads
I switched to only paid relays and haven’t seen any since
Some of us are planning on deploying small personal relays. In that circumstance, we are on the hook for moderating our own spam.
I didn't mention NIP-56 kind 1984 reports. But subscribing to those and treating them judiciously can also help.
I think small relays are the right way to go. micro relays, micro apps. everyone will be happy.