Theresa identified some ways to respond constructively to editor suggestions. I just want to add, stay open. No writer is perfect, and until you earn a publisher as much as John Grisham does, expect to be edited.
If an editor has no suggestions or edits, sure, it might be your book is perfect, but what it probably means is that the editor is too busy to take any time with your story. Editors do sometimes have to practice triage, you know. If another author has been ill or had a family problem and delivered a very scratchy ms three months late, and it's due to the typesetter yesterday, the editor is going to focus on that. If your story happens to arrive right then (because YOU met your deadline, hurrumph), it's probably not going to get the attention it might otherwise get, and might need. If this happens to you, go through the ms again-- you'll have a better understanding of it now that you have some distance. Line edit it yourself (but tell the editor, so you don't end up with two different versions), and send it in-- "I thought I'd take advantage of the extra time to take one more pass--"
Anyway, don't ever take an editor's suggestions as an insult. But don't expect a lot of compliments. If your story wasn't good, it wouldn't have been bought. Quality is a given. The editor is a problem-solver, and focused on problems, and that's what she's going to spend time talking about.
Of course, there are suggestions (or edicts :) which are outrageous, plain and simple. Again, get a much-published author drunk and you'll hear about them. (The secondary character turned into a rodent, literally, for example.) Then what? I'd say, wait a week or so, talk to some trusted and experienced friends to make sure this is really outrageous, and then go over the editor's head. Yeah, I mean it. Editors aren't infallible. And the managing editor might want to know if an editor is not doing a good job.
BUT... consider if this is worth fighting about. Those multi-published authors with the horrific stories? I bet most of them swallowed their pride, accepted the edits (or deputized their agents), and kept their careers. The last thing you want is a reputation as "impossible"-- so really, really think this through. YOU think it's an outrageous change... will the managing editor? We've all had writers who thought every word was golden, and they MEANT to dangle that participle, damnit, it's their VOICE to dangle participles!!! And you sure don't want to go to the mattresses for the dubious right to dangle participles, because you know what? The managing editor is probably more likely to agree with the editor that dangling participles are evil, go figure.
Finally, no matter what, don't trash the editor or publisher on the internet. Duh. You know that. And yet, impelled by righteous indignation, a lot of authors have done just that. Complain by phone, okay? Call your friends-- complain to every single one of them. That's what they're there for. But phone calls are ephemeral. No one is taping what you say, and it doesn't last for more than a day or so. Anything on the internet lasts forever, and everyone who reads it is NOT your friend, and the insult is easily forwarded. If you cannot bring yourself to say this to the editor's face, do you really want it forwarded by someone reading your blog? The editor WILL see it, and maybe even other editors. You might not mind burning your bridges with one editor, but how about all editors?
If you have a complaint about an editor, take it to the editor's boss. But wait a while. Consider, just consider, that you might not be the best judge of whether you're right or not. None of us can be truly objective about our writing. So take some time. Consult with others. And tamp down the rage and listen. If your friends are lukewarm in their support, that could be their friendly way of telling you that you're wrong.
One more thing-- if you are, in fact, a good writer, you should be able craft an email that has a constructive and courteous tone, that finds common ground and presents useful alternatives. If you can't do that, you're not likely to convince the editor or the boss that you're right about your own stuff (even if you are). We all know that emails written in the heat of passion are seldom the most reasonable of missives. So whatever you write, even if you think it's nice and neutral, take a day or so and read it over.
It's hard to know, isn't it? Is the editor being unreasonable? Are you too sensitive? You really can't know. So what ever you do, do it knowing... you could be wrong. Always an uncomfortable realization!