Wow, good to know.  I have not yet seen one of those here on nostr.  I have already prepared my response that I will cut-and-paste if/when I get a hello.

them: Hello
me: To combat bots from sending me hello messages, please send 2100 sats to versiebtc@getalby.com with a comment of "hello from [your name]".  I will see it and decide if I want to respond to you within 72 hours.  If/when I do respond, I will send you your 2100 sats back.