Double Negatives: Writer Beware!

       Today's (Jan. 5th) L.A. Times has an article on the release of Vladimir Horowitz's Carnegie Hall recitals over 35 years:  41 CDs.

       The caption under a photo of the musician at the piano reads
VLADIMIR HOROWITZ performs in 1965 at Carnegie Hall, a venue whose               importance to the pianist's career can't be understated.
Most likely the caption writer made the mistake; the author said "overstated" in the body of the article.

       Let's see:  "Was Carnegie Hall important to Horowitz's career?"  "Uh-uh.  It was unimportant.  No, it was really worse than that.  It was terribly unimportant.  Somehow that doesn't do it justice.  Carnegie Hall meant nothing to his career."

       Using a double negative or a negative plus something like "overstated/understated," be careful you don't contradict your own intended meaning!