Of course there is no kind way to say we don't like your work, but surely there is a way to say it in the vein of it's not you, it's me.
I don't think any writer relishes the time and effort spent packaging their work to meet each agent or editor's individual specifications...query only, query and synopsis, query and first 1000 words, synopsis and first three chapters.... You fellow writers know what I mean. My favorite is that simply requesting a synopsis isn't good enough anymore. Apparently there is a regular synopsis of 4 or 5 pages, a one page synopsis, a 500 word synopsis and who knows what request I'll have to fulfill next! Don't they get that if I could fit the action, plot and characters of my manuscript into one page, I would do it to begin with?
But nonetheless, I methodically give them what they want and send it off hoping for the best.
Then the rejections start coming back. Now, it's not that I don't expect a fair number of rejections. I do. But it is the way the rejections come back that has begun to irk me. The ones I have received come as form letters on photocopied paper with the left margin faded like their printer was running out of ink on the original copy. They come without letter heads and unsigned...and my favorite was the rejection postcard.
Couldn't these agencies - that make their living off of our work - at least fork out an original print on letterhead so that we feel rejected by a classy, sought after firm? That would be easier to stomach. The ones I receive make me feel that I've been rejected by the last surviving agency on the planet in the slums of the publishing world.
The last rejection I received simply said "I have reviewed your material and it is not anything I wish to work with at this time." Ouch. That's like saying 'you look nice, but you're not anything I wish to date right now.' When then? Maybe when hell freezes over? When all the good stuff stops rolling in? I much prefer the kinder, gentler approach: Thank you for your submission, but I will not be able to represent you at this time and I wish you best of luck with your manuscript.
After all, there's no reason to be rude...I know what you mean either way you say it.