Oops, so sorry, Grendel, no offense intended (my musical associative memory must have played a trick on me <BG>). And pardon my generalizing, please (I tried to wrap it in a "at times", but to no avail ;-) ) -- of course, it's mostly a matter of the invidual style, not mainly one of the medium, nevertheless I can't quite overlook the finding that many writers in web media tend to use, say, sloppy language, at least sloppier than what they might use in hand-written or official statements.
Coming back to the original question, I read Becky's comment with great interest, as it seems to not only back up GeorgeA's assumptions (and mine), but present an answer as to the meaning of 'doof' as an English noun.
Last remark: In my home dialect (Rhenanian), there's the same use of 'doof' as noun, e.g. in the humorous snubbing "Do bess ävver en Doof / Döövche!" (= "You're kinda dumbhead!"). Since dialects generally preserve old traits of a language much longer than the so-called 'educated' language, it might well be the case that said use has a common root. Moreover, it isn't commonly used in written texts, neither here nor there.