I've read about everything I can on the 5D being a dust magnet.
I don't have any reason to believe that something electronically in the 5D "causes" it to attract dust more than another model.
However, I CANNOT keep my sensor clean, even while NOT changing lenses.
I read that Micheal said he thought the 5D was a magnet, but now he doesn't.
This leads me to believe that the 5d's mirror box internal anti glare coating flakes off and lands on the sensor, until all of the "extra" coating that will flake off has flaked off.
I have no evidence except that I can clean my sensor, put the lens back on, turn the f stop up to f22 and take a picture of a neutral background. I see a very clean image. After more pictures, and maybe several days in between examinations, I start to get "dust" marks YET AGAIN--without changing the lens. Sometimes it's only a matter of one shooting session.
Anyway, for what it's worth.