All of which means I'm grumpier than usual. So when I come across someone saying 'disinterested' (which means 'neutral', 'impartial', 'having no vested interest' or, as Fowler* says, 'free from personal bias') when they mean 'uninterested' (which means 'not interested', 'bored', 'un-engaged') -- when I see that in print, which is to say in a piece of writing that at least one editor has seen and passed, I remind myself of The Test.
I've read four novels a week for review (and often more than that, for pleasure or for other work) since Boxing Day 2007, which adds up to 240 novels since last summer. So I've had some serious recent practice at making quick general judgements about writing skills.
And 'disinterested'/'uninterested' is the ultimate pass/fail test. It means that not only does the writer not know the difference, but the publisher has employed an editor who doesn't know the difference either. And people who haven't yet arrived at this threshold of language skills should not be writing, or editing, books. Any novel in which this usage appears immediately goes on the B-list, and immediately makes me more suspicious of the writer; if s/he has committed to paper this very common and much-talked-about
I apologise in advance to the oft-generous folks at Language Log and all who sail in her for still caring about this at all, much less fighting a Quixotic rearguard action on it, if only as an unvoiced factor in my judgements about fiction. I'm with the also oft-generous Fowler (or possibly Gowers, who was responsible for the revised Second Edition), who in the entry on 'disinterested' reluctantly admits both usages but remarks wistfully at the end: 'A valuable differentiation is thus in need of rescue, if it is not too late.'
*As in Fowler's Modern English Usage. Tried to find a decent informative link and stumbled instead upon an online encyclopedia with an entry by one James Munson on the most recent edition of Fowler; much of said entry is taken up with a scornful rave about that dreaded scourge of our times, Rampant Feminism, and the linguistic Political Correctness that allegedly followed in its wake. All this is, of course, says Munson, "errant nonsense". He means "arrant".