Many of us don't open threads we don't like the sound of title wise. Then when the thread keeps on going and the contributions mount we think, 'Better take a looksee'
The last post says something you don't agree with, or vice versa, so you look back a couple of threads to see what caused the posting, you disagree with the premise and think you can say it better, and then you post.
The fact that your finely honed prose may be an exact duplicate of one posted 2 days previously doesn't matter, you're never going to read it, you're never even going to know about it unless some school swot draws your attention to it. The chances are though that the next contributor will do the same as you just did, and so the cycle continues.
Then there's the monoposter thread, where most of the contributions are from one poster, and you sort of feel it would be crass to gatecrash the posters little Narcissistic noodles.
I really think a thread classification system should be set up as just Music and BS are not enough to either attract or warn the possible poster of the contents of each particular post.
Something like.

1 Post liable to bore you to death
2 Post liable to raise the blood pressure of Republicans
2a "    "    " "      "    "    "      " Democrats
2c                                           Brits
2d                                           Americans
2e                                           Canucks
2f                                           Grammar policepersons

There might just not be enough room for all the different classifications, but hey I can think of a couple of anal Catters who would just adore being asked to draw up a list of post contents labels.
You know who you are!!
Giok