Michael Hyatt, the CEO of Thomas Nelson publishers, recently posted this great column, which anyone putting together a book proposal should study closely. Granted, he's talking about reading books -- not proposals -- but many of the same principles apply.
Years ago when I was working at Servant, our marketing/sales experts used to say that it takes seven seconds, on average, for a customer to decide whether to purchase a particular book on a store shelf. Seven seconds, on average, to study the front cover, back cover, TOC, and first couple of pages.
The same principles apply to proposals. When I was going through the slush pile, it took about that long to evaluate a proposal for possible publication: cover letter, TOC, and first three pages. If at any point it didn't grab me, I'd put it into the reject pile.
Could your query pass the seven-second test?