If you go back to my first post, I had said that I feel that a martial artist is anyone that trains. For me, I consider training, to be defined as something someone does on a regular basis, ie: attending class 2-3, if not more, times a week. IMHO, attending a 1 time womens SD class for example, no, I wouldn't consider those people martial artists.
To answer your above questions...as I asid in my initial post, again its anyone that trains. A white belt is just as much of a martial artist as an orange belt. Its the training that matters, not the color of the belt, the fancy certs, etc. Why do I say that? Because IMHO, its the training that will be called upon, should the person need to defend themselves. White belt, yellow belt, brown belt, is all moot....those're just symbols of where you're at in your training.
Is someone who trains at a mcdojo a MAist? Yup. Does the BB who sucks still a MAist? Yup. And yes, of course they can suck.
Once again, as I said, those people, despite their actual ability or where they train, are still MAists.
Quality of said dojos or physical skill of the person attending, are topics for another thread.