As with most things, context matters. Correcting someone’s casual speech is assholery (usually). Offering unsolicited corrections to a piece of professional writing or public speaking can be welcome, if offered privately or in a forum where it is expected and common, like the corrections to my blog posts that are offered here. (I don’t count unsolicited corrections to apostrophe use on hand lettered signs at the greengrocer’s to be “professional.” That’s always assholery.)

Can I just say how much I enjoyed this whole thread? Reading it in a single sitting was simply marvellous. The bit I loved best was

graviton - 23 December 2012 06:54 PM

Mary McCarthy and Lillian Hellman (since I now know you’re a Brit, let me just say that the two women were American literary figures)

which, if truly said with naive lack of awareness, was just stunning, and even as deliberate trollery was particularly fine. But while the soloist’s contribution was, of course, essential, none of it would have worked without the ensemble playing of the Wordorigins orchestra, each member giving of his or her very best. You were as polite as possible, you were informative you were amusing, you were forceful. Thank you. Thank you all.

I loved your critique, zythophile. Spot-on.  It is indeed an ongoing delight, and a privilege, to participate in a forum with contributors like these. I heartily concur with your appreciation of the wordorigins.org ensemble - it is something really, really special.