I have watched a lot of commercial television "news" in my life, and I think the sort who think it "liberal" are the sort who use "liberal" to mean, "of the sort of ostensibly law-abiding, apparently normal person who is nonetheless going to hell because he's not a member of my church and in perfect agreement with my rather strict and exclusionary religious biases." Ahem.
From a moderately leftish or centrist point of view, the talking heads on CBS can be pretty scarily authoritarian--Bob Schieffer is practically calling for Edward Snowden's head, which makes me wonder what he thought of Woodward and Bernstein--and "conservative" in a small-c way. And some of ABC's regulars are practically GOP partisans; ever watch "This Week"?
This is just my perception from actually watching them. One possible explanation is that, "everybody knows" that liberal bias is endemic, so each channel must massively "overcorrect" to keep from offending the ostensible majority of Americans who are "right-thinking conservatives." But the effect is massive bias toward white conservatives on most issues. This is despite the clear embrace of affirmative action in their own hiring, and their recent embrace of gay rights.
Statism? They're authoritarian, and seem to think the Rosenbergs got what they deserved, and Snowden deserves the same.
Culture? They encourage an idea of Santa Claus invented by Macy's or something. Ronald McDonald taught them how to eat.
Foreign policy? Iran is seen as always evil and untrustworthy, Cuba is apparently not being oppressed by the blockade (or is but deserves it), China stories must be treated with kid gloves to avoid offending either corporations that manufacture there or anti-Communists, and we "belong" in Afghanistan.
US political history? Reagan was the father of the country. Harry Truman, LBJ, FDR, heck, the entire labor movement and liberal consensus--may as well have never existed.
Politics? All horse races, and they hope "the right kind of people" win.
Social ills? The news guys don't say it, but the Hollywood fiction factory they pimp for will: The inner city is thought to be full of dumb poor niggers in hoodies who live lives of crime in gangs.
Liberal? Conservative? Try "establishment Americanist" with a side order of "loving Big Brother because it is impossible not to," and one notable cleavage in that some of them still want a white Anglo society and some are more accepting of latinos, some blacks, and south Asians. So small-c conservative, but too progressive for a fringe of religious and cultural extremists.