Many of the current iteration of spam bots have cryptocurrency in their mxid. If you see someone with a cryptocurrency mxid join, immediately ban them.

They also seem to join 100s or 1000s or even 10 000s of rooms before they spam a message. If you are in like 3 medium sized rooms with completely unrelated topics, if you see @robbert joined all 3 of the rooms within an hour or so, pretty good chance it’s a spam bot.

Earlier iterations had profile picture of real people, prob taken from instagram.

Mostly crypto spam, but i’ve seen one selling graphene phones.

If they aren’t banned, they will sometimes later activate again with a new ad.

Should be possible to do with a bot too, if anyone comes across one that i dont have to self host hmu. If you don’t want to ban, you can mute them and tell them to DM you their favorite color to prove they are made of flesh.