For me it's very simple.
On any given thread that I might want to read (and I don't read them all any more) I quickly scan down the column of posters to the thread. Over time I guess we form impressions of those we deem credible or "like-minded" and those we don't. Everyone's tastes are different. When I see a thread with a list of names of posters that I've determined as not relevant to my tastes and opinions, I leave the thread without reading its contents.

If I see that the majority of people who contribute to a thread are "like-minded" individuals I'll peruse the thread.

In the beginning I did read all of them, in order to determine who's worth listening to and who's not relevant to my ongoing Mudcat experience. When new members come on board, initially I will read their posts as well and form my own opinions and decide to read or ignore further posts from them.

I also like to play a little game with myself when I see certain new threads, and ask myself in advance before opening the thread, who started it. 8 times out 10, I guess correctly.