Mr. Hyneman, however, insists that he and the "Mythbusters" team "don't have any pretense of teaching science . . . If we tried to teach science," he said, "the shows probably wouldn't be successful."
Even if they aren't teaching science, they are approaching problems using experimentation. So, they're doing science (minus the whole 'replication' thing), even if they aren't calling it that.
well, it is teaching science by teaching how to develop an experiment, and even to the point of talking about what variables they tried to control and why an experiment might have failed.
it is showing the scientific method: research, hypothesis (do we expect to bust the myth or not?), more research to build the experiment, review in a larger community how the experiment will address the hypothesis, build and conduct the experiment (with variations to try to help isolate variables), and reach a conclusion.
this is what is taught at the middle-school level. the larger scientific process (publish in peer-review and let others try it) is left out only because the methodology and subject matter isn't precise enough for Scientific American and the there's always those key words: don't try this at home! :)
so the only real factor is having an independent review look at the methodology after it's conducted, but it teaches enough skepticism along the way that it can become an "exercise for the viewer". the viewer, the audience, then becomes the "peer review".
I think it's science at a level that popular culture needs. as a first step at trying to get science back onto television with an audience willing to watch it, I think it works well.
Mythbusters lacks a few other aspects of actual science, too. For a start, they make constantly the "correlation equals causation" fallacy. Moreover, their reasoning on physical matters is often poor. They tested the myth about a cherrypicker acting as a catapult, and it failed (of course) but then they suspended the cherrypicker between shipping containers and tried to catapult their long-suffering crash test dummy, Buster, by pulling it back and releasing it. Of course, Buster, being constrained by the cage, inscribed a circle and was dumped at the end of the rotation - hasn't anyone told them about centripetal force? The reason why trebuchets release the load at the top of the arc is because if they don't, they will do just what happened to Buster. And anyone could see that from the way they set it up.
But it's fun, and they do blow things up a lot...