Sometimes they’re desaturated.

Sometimes they’re 3:4.

Sometimes they’re straight-up black and white.

Changing something about the appearance of of the image is done often. But I don’t think blurry would do unless it’s a really short flashback. It would either look like a mistake (camera not in focus for instance), not be intense enough to be apparent on smaller or lower resolution TVs, or be distracting and annoying to the viewer (say, some sort of foveated motion blur).