With the decline in Usenet traffic, that's much less of a problem nowadays. I haven't seen any spam in comp.lang.lisp for the last 2 years at least. It's pretty much all signal, and mostly high quality too.

You must have some kind of spam filter. Of the 6 (six!) postings to comp.lang.lisp over the last week, half of them were some political anti-cryptocurrency campaing in Italian. But yes, a few years ago it was much worse.