Instead of deleting it, I think we better replace it's content with something more meaningful, not necessarily related to Atlassian, but at least informative.
Of course, retagging should be mandatory, let's say to "former-spam" or "intellingent-spam" or something (open to suggestions)
Like for instance, I was reading today this article: http://www.theregister.co.uk/2011/08/30/veggies_in_spaaace/ and if I want to share it with you, I would edit the first spam and change from "Cheap watches" to "Lettuce in space", and retag the thing to "former-spam".
Instead of fighting it all the time, maybe it's time to embrace it, our way.
You can get more social that that.
What do you think ?