I wrote:

Has anyone had any luck filtering the nonsense posts using
the agent newsreader? It allows one to filter on subject
and author; I cannot find any other criteria to filter
this/these pests out.

Thanks to Dave, Kay and Andy, etal for the replies. I ended up with an
Agent newsreader filter shown at the bottom. I'm in the U.S., the isp
is useless filtering this stuff and I want to stay with Agent as
newsreader.

Dave
I am using a filter to delete all posts over 60 lines in length. This gets
95% of them.

Kay
And guess what ... they're now all under 60 lines. Can you imagine
someone having so little to do with their life that they actually read
what people are trying to do to block posts?

Indeed, shortly after I put my filter in place many posted were to 3-4
lines.

andy
Delete [40,*]

This is the filter I put in place:

subject: * &[65,*]

This obviously has to be set for urg and not globally.

Kills everything for this group at 65 lines plus. This took care of
thousands of the nonsense posts. And as Kay mentioned, now the pest(s)
are posting with 3-4 lines. Doubt there is much that can be done about
these with Agent without killing the useful posts.

If anyone can post the url that was mentioned a while back on how/why
these are generated, I'd appreciate reading the explanation.