Thanks to my friend Richard
(by the way, welcome, finally, to the blogosphere), I realize the spammers had evened the score. The spammers had posted their csaino (sic) and icnset (sic) spam on my site again, despite my workaround.
I never claimed my workaround was particularly sophisticated or unbeatable, but in response, I've upped the ante. Again, nothing impenetrable, but just enough unpleasantry to make myself less of a target.