Dear Miss Snark,
As snarky as you are, I'm sure in your career you've sometimes had to write the inevitably tearful letter informing a novelist that although you dearly loved his book, you have to turn it down, but you're certain he'll be snapped up by the very next agent he submits it to.
My question is: what are you really trying to say? If you love the book so much, then what's preventing you from taking it and sparing us both a lot of agony? If you didn't really love it, why didn't you just reject it with a form letter? (Or, is this in itself a form letter?) In any case, is there something an author can do--within the law--to turn this around, through persistence, ingenuity, revision, chocolates, celebrity endorsements, having an excerpt published in a literary magazine?
Have a nice day (within reason),
Well, as you might expect, I never write letters tearfully saying I love it but can't take it on. I say things such as "I like this but I don't think I can sell it". And that's the dog's honest truth. I can't sell private detective novels to save my life right now. And I LOVE them. The market just isn't there for new ones. Or at least for mine. And really, that's the measure ... do I think I can sell it.
Alternatively, if I like something but you have proven to be a complete and total pain in the pita bread to be around/work with/deal with, you are "not right for my list" and will probably be much happier down the road anyway, so here's a rejection letter to get you started.
As to the form letter, if I've read your whole novel, I write you a realio trulio one of a kind letter. Try not to parse out hidden meanings. The only meaning is clear: no.
If you're getting a lot of "I love this but I have to pass on it" just keep sending queries. You'll hit the jackpot eventually.