I used to report posts all the time when I first joined. Quite frankly, I was getting tired of seeing those atrocious foul-worded one-liners and dupe threads/posts that were prevalent around the time SS was released when the Skyward Sword section was brimming with activity. I barely left the SS section during that time, so it was only right that I helped keep my [then] favorite section of the forums clear of spam, dupe threads, flaming, and trolling...
I don't report threads very much these days, seeing as I come across them less and less...