..."The Sporting Life" on ESPN radio.
There was a segment on the golfer Erica Blasberg who committed suicide last May, part of which report included her suicide note.
Aside from the waste of a life cut short, what struck me, as I listened, -- as a teacher of writing -- is that I can't remember coming across a suicide note (in newspaper stories or other news reports...luckily never firsthand!) that was poorly written (i.e., that contained the kind of typical writing errors that plague most assignments/everyday writing/emails/blogs/tweets/facebook posts, et cetera).
Now, one would think that, in many (most?) cases, people who are about to take their own lives are not in the best mindset to clearly state their thoughts and therefore would write the kinds of run-on or incomplete sentences or include dangling participles, misplaced modifiers, or instances of subject/verb non-agreement so rampant in writing everywhere else....
Then again, perhaps this is when people's thinking is indeed the clearest, and their written expression simply reflects that clarity.
Yet another possibility, of course, is that only those who have really thought such a serious course of action through write suicide notes ... or no one actually quotes poorly written ones. (Remember, always place a comma between "Goodbye" and "cruel world.")
I'd wager there's a study about this being done (or that has been done) somewhere.