To be honest, some of my posts are not even worth mentioning.  I guess my point of view is different than other peeps, but I still express how I feel.
I guess the meaning of "spamming" a thread is saying just nothing to make your post credible, a nod.
We're all guilty of that.  But then again, the acknowledgment is a good thing.  I suppose that's why there are users that are wary of saying anything because they may feel stupid for saying something that has already been said.  
*?*
If you don't say anything, how can there be an acknowledgment to begin with?
I don't know.  The "Spy" thing that Hoff mentioned makes sense too.  Then there is a new user that posts in a Necro thread, but it encompasses something that they were meaning to discuss?
I can see both sides of the coin here.  It's all well and good until it gets out of hand.
Ah, what do I know?