First off, if you feel anyone is spamming send the list to a global moderator or an admin for consideration, and if they do not answer back then consider making such a thread.
Secondly, local spamming is hard to clarify because many people might be willing to post more in their own language, or they don't know english at all, should be clarified with the Local mod of that section
Thirdly, I don't see much of spamming from these guys. Seems constructive posts to me, and a post doesn't have to be either lengthy or timed to make it look non-spammy
Fourthly, all signature "spammers" are here:
https://bitcointalk.org/index.php?topic=973843.0I would refine it down to: