^I've seen the trope deconstructed now and then, but not often enough. Futurama
made a joke about it in one episode. FlashForward
did a pretty good job of rationalizing it: They were able to enhance a blurry image, but only by sending it to the top specialists, who spent weeks extracting data from multiple video frames and combining them into a composite, and even then, the final result wasn't very clear.
As always, TV Tropes is a motherlode of examples, both of the trope and its occasional deconstructions: