Is this a poll or a survey?
"Noncoherent" seems to be used mainly in physics or math. Generally you'd say an "incoherent question," not a "noncoherent question." Both terms are defined as "not coherent" but they seem to refer to different definitions of coherent. It would be nice if dictionaries were a little clearer on this distinction. I can't say the phrase "noncoherent question" is incorrect, strictly speaking, but it's certainly nonstandard.
Am I a lady? Why for heaven's sake do you think I call myself "Bro?" Please strive to be a little more perspicacious, folks.