I can’t seem to find it. Please help!
This could be the one you’re thinking of, maybe.
Are poor spellers stupid? October 21, 2011.
Here’s another honorable mention – although the OQ (original question) isn’t directly about grammar or spelling, it does seem to point at the quality of some educational circles in alabama.
How do evolutionists explain the Big Bang, the fact that we haven’t seen animals evolve, etc.? May 17, 2000.
The OQ here resembles one of those thought experiments with the ten million monkeys randomly banging away at typewriters, one of whom just came close to writing something intelligible.
That wasn’t Cecil, it was a staff report.
Found it! This was bugging me - I first found the same one as Senegoid, but it didn’t seem quite right.
That’s it Troutman. Thank you!
Heh, it seems to me poor old Cecil was being massively “wooshed” by the letter writer … ! 
(Or perhaps we were).
The tip off? “I am sending you a copy of this letter I wrote to [San Francisco Chronicle columnist] Herb Caen at the urging of my husband. He says only a man of your intellect and discrimination can truly appreciate all its nuances.” [Emphasis]
Reads to me like the letter-writer deliberately dropped a bunch of bombs for Cecil to find. The writer isn’t actually asking any sort of question.