And when they do provide investigative reporting they often leave out critical pieces of information to "slant" the story whichever way they want the audience to go. Does anyone remember the debacle with Dan Rather and CBS news over the fake memo about President Bush just before the election in 2004?
The bloggers started picking the story apart very quickly, but CBS kept sticking to it and calling the bloggers untrained amateurs in their pajamas. In the end the bloggers were right and the story was proven false and they [Dan Rather and CBS] had to offer an apology.
I think having alternative news sources out there is important, but I do see the point that this can cause a problem with verifying real information and sources. Unfortunately if CBS can lie so can everyone else. I am not sure what the solution is except cross checking all your information against multiple sources.