Writers are always told how very important the query letter is, and to back that up I sometimes mention the fact that my original query later became, almost verbatim, the backcover copy of my novel.
Well, today my UK publicist sends me a review of my book that appeared in The American, an expat magazine. It's a perfectly fine review, but I can tell the reviewer simply adapted the backcover copy as a solid third of her 200-word piece.
That means that effectively, my original agent query has now become my own "objective" third-party review.
Good thing it's not a bad review or I'd be very annoyed with myself for having such a low opinion of my work.