In a comment to a thought of the day, one reader said:
Frankly, I don't understand why you would necessarily reject the next blockbuster just because an author has an ego problem ('all other books suck' etc), or because someone says their book 'needs an edit.' You know very well they all do.
Because no one knows that your book is going to be the next big blockbuster. Heck, I don't even know if your book is going to sell. Every agent has taken on a project confident that it would sell and become a success, only to find neither was true. Every single agent has had what she deemed a "sure thing," only to find it surely wasn't. Why would I reject a book based on the negative things an author says in a query letter? Because I'm going to have to work with this author for the long haul. I'm intending to work with the author through revisions and rewrites, rejections and offers, negotiations, next books, career planning, career moves, market lows and market highs. Because I'm expecting that we're going to be together for a long, long time and that it's not always going to be pretty, and I want to know as much as possible that the author is ready for all of that, is ready to work hard and, more important, that we can work together.
In addition to that, if you're telling me that your book isn't its best, then isn't that telling me that reading it is a waste of my time? I'm looking for fabulous books that are ready to be sold to the market. Sure, I might need a tweak or revision or two, but if you, the author, are telling me up front that you don't even think your book is ready to be seen, then isn't that reason enough for me to know it's not ready to be seen?
And just to be fair to the reader, I wanted to share the last statement of the comment: These sorts of poorly thought out rejection lists harm an agent's credibility.
And say that I'm sorry if telling the truth harms my credibility. I thought it might actually help you write a stronger query.