Miss Snark: I hope this isn't a nitwit question but... What does it mean when an agent tells you they liked your material but "it would be a difficult book for us to market"? Is that just a kind way of saying your writing stinks?
Nope. It means they can't think of who/where to sell it. "Your writing stinks" is "not right for us at this time".
PS: "not right for us at this time" doesn't always mean your writing sux. But if your writing sux, you're not going to hear much beyond "not right for us at this time".