Guess who wrote:

Hi,

I thought I'd drop in and sampel a few messages. All were on
politics. Am I in the right newsgroup?

It's an election year here in the US. A lot of newsgroups are suffering
from the same garbage.
Ignore the garbage and sample the ones you are interested in.
If you find they are helpful, then filter out the garbage with your
newsreader's tools.
You can filter the headings you don't want, which will filter all the
subsequent threaded messages, or you can filter the sender (but you'll
still see the responses), or you can filter both.
The messages tend to stay on topic after that.