Unless I misread your blog (which I love!) and totally misunderstood (which happens to me sometimes), it seems that an editor who rejects with "this isn't right for me" is nicely saying "your writing isn't quite up to par".
I've got two rejections of this type from editors responding to my agent's pitch, although both love my premise and hope I find the right home for my novel. So my question is this: are they really speaking in code and saying my writing isn't up to par? Or are they really just saying what' on their mind and that it isn't right for them? My agent says not to worry, this isn't necessarily indicative of where I'm heading because it's only two rejections (and he has many more editors to pitch to). But it still makes me wonder.
Wonder not. Your agent is right. If your writing sucked, you wouldn't have an agent. Believe that if you believe nothing else.
Editors don't have the luxury of publishing everything they love. They have to answer to the higher ups who will point out that the last book XYZ published about dancing poodles did a major header DOWN the sales charts. Woe to the next dancing poodle story, regardless of writing.
And editors don't like everything that's well written. All you have to do is publish a list of "Ten Books That Rocked My World" and you'll have differing opinions coming out of the woodwork, thick on the ground, and cluttering up your bandwidth.
Writers obsess. It's one of the things that makes you good: obsessing about words, rhythm, punctuation, character, plot, and all the other things in a novel. However, obsess ONLY about the things you have control over. Time to go obsess about that tricky bit of dialogue in chapter three of the next novel. Leaving obsessing about lamebrained, half wit, slimey...err, I mean over worked and under appreciated editors to your agent and me. We've had LOTS of practice.