I do that mainly by quoting aggressively the jobs that suit my operation well, and quoting the more fussy jobs high.
This is common practice and there is nothing wrong with it; but why not just say "not interested"?
I make my own products so I don't normally take on customer jobs; maybe 2-3 times a year. However, I do sub out my production so requesting quotes is something I do more often.
I do not like sending out half a dozen rfq's for the same job and I hate sending rfq's to a shop that I never award them to; it makes me feel like I am wasting people's time. If it happens enough, all of my quotes will start coming back with a silent "annoyance fee" added to cover their time that I have wasted - you can't tell me I'm wrong either lol.
I cannot speak for every customer but for myself, a high quote accompanied with a note would be helpful. Something like; "not a good fit", "features x & y are time consuming", "bend tolerance requires special attention" or even just; "oh hell no, I want no part of this job."
This way I can make changes to simplify the design. Basically; is it expensive because the vendor doesn't want it? Or because my design is flawed? If I don't know that info, it could take 2 more weeks of submitting and waiting on rfq's to come back before I know for sure.
If design changes are required to meet my profit margin, I have just wasted the time of 3 vendors and gotten myself 1 step closer to slow quotes, ignored rfq's or an annoyance fee.
Hopefully this doesn't derail the context of this thread. It doesn't need discussion; consider it more like rhetorical customer feedback I suppose.