Yes I did it a long time ago, long before the OP created this thread.
In the sports related threads, I tend to delete low quality posts including those that are from members spamming for the sake of their signature campaign fee. I think it helped in many ways to keep those threads clean. Sure it has resulted in less number of posts compared to similar threads but that does not have a negative impact because the regular visitors continue to post.
If i give my own example, i am a big fan of cricket, so i usually post in cricket related gambling discussion threads. Even though those threads are over 500+ pages but I still find them interesting as we have new matches and tournaments every now and then and i always have something new to discuss and read. There are many regular posters who discuss the same and even if a newcomer comes there, it is not easy to recognize (unless he says anything foolish) if he is posting for a signature campaign or he is really interested in discussions.
Since I rarely follow football leagues or other sports, you won't find me posting there. Even if I had to post there, I would have something to say about it and not spam.