The various popular science magazines, TV shows and the like aren't all bad or good. It depends on who is doing it, the topic and what audience they aim for.
Generally, there is a big problem with complex issues that are at the leading edge. The producers have to aim at a middle of the road audience with a limited attention span. How well they simplify varies a lot. Somethings when simplified aren't really right any more. How close they can get to conveying the right message is tricky.
It also depends on what you bring to it. If you have an extensive back ground you might get more of the "truth" out of a show or be able to see where they have over simplified. An example might be the global warming issue.
There might be an argument presented between two scientists with differing views. One might say "we have shown that global warming is partially caused by man". The other might be shown saying "it isn't proven".
This may appear to be a big difference when they might, if brought together, end up saying the same thing.
"we have shown" might be short hand for "the correlation between what we observe and the expected effects of the measured CO2 increases make it relatively unlikely that the change is a part of natural variation"
"not proved" might mean "the direct linkage to carbon emissions and precise changes in climate have not been shown. We still don't have all the information on the carbon cycle as it is currently running."
With the above translations both claims could be right. However, you'd have to know something that the show isn't going to have time to air and know a lot about the nature of scientific thinking before you could suss that out.
Without the background you'd just come away thinking that there is a total disagreement with only a black and white decision to be made. This would be terribly misleading and you would have no real idea of what is actually going on.
This is one reason why popularizations can be iffy in complex areas.
Add to that the need to jazz up a show by making it appear that there is controversy when there might not be and the rush to air that some shows must do to keep costs down and there is risk in taking them as your source of information.
The magazines that offer a chance for questions and disagreement to be published as letters to the editor seem to me to be more trustworthy. If you follow a topic from initial publication through a round of leter writing you get a bit better an idea of just how well accepted an idea is.
I like "New Scientist" myself. It isn't at too high a level but not as low a level as "Scientific American" as settled to. Discovery seems to be ok but I don't read it all that often. It is a bit lighter as well.
A better option is to get more than on book out of the library on a topic. If real experts in the field right them for a popular audience you get a much more detailed insight. Then read any differing views you can find. By the time you've done that you probably have as good a grasp as you're going to get.
The only real source is primary literature or books written that intend to be at that level. They don't all have to be unreadable. (It just seems that way
)
With the resources here (at evcforum) you can probably get reasonable views on anything you see on Discovery channel or read somewhere. The real scientists here do have some expertise and insight that should be helpful.