I think there's a very fine line to be traced with spam. For instance, I think it's way better to have a one-liner "I agree with _____" thant having a HUGE quote (like I see in some other forums) and a Q4T under it, just for the sake of having a big enough post. However, I think there are those cases in which a one-liner may be out of place, and I think it's fine to just delete it (although I think that, when we delete someone's post, we should have the system send them a PM with whatever we wrote in the "Reason for Edit" box (which we'd have to fill even when deleting a post, then). I also think we should cap the number of offenses (perhaps having a 3-strikes policy, with a one week ban from a particular board or such, if it comes to that).
That being said, I'm all for a harmless spammy post every now and then when it's funny and at least remotely related to the topic (I don't want people to spam about posting jokes on random topics, of course), but that tends to derail fast, as other people will then barge in saying "SPAM" and etc. What I usually do is delete THESE posts and leave the joke, but I think it'd have to be made pretty clear, otherwise we could be accused of protecting certain members, etc.
Also, I think foul language and unnecessary rudeness should get a 1-week ban instantly, no prior notice. For all I care, GT should've been banned from the CoC for the stuff he posted when he popped in, although he's been working on improving lately, from what I've seen. However, I still think a steady hand might be needed.