A couple of the "no" responses are very nice, in that they are obviously personalized: they compliment certain aspects of the story and mention what didn't work for the editor. Definitely not a stock response like "doesn't suit our needs" or "not right for us".
The question is: Do I send a short "Thanks for the consideration and the feedback" note? I'm certainly *not* talking about a "You obviously don't understand MY GENIUS" response.
One, because the feedback is valid. I might or might not act on it, but it's valid and I understand what they're saying.
Two, because a "MY GENIUS" response is a one-way ticket to the "Banned" bin along with fodder for certain Internet humiliation :-).
But do I send a thank you note? What do other writers do? What do the editors out there think of a short "thanks for the feedback and the consideration"? (Which could sound like a stock response from me!)