Journalists favor one political party over another - and their reporting therefore casts one positively and the other negatively.
Journalists don't do the research on a topic to explain it factually and end up looking silly. No kidding, I was at the station and the reporter talked about the local police getting AR-15 rifles. They showed a graphic of a .50 calibre sniper rifle. I pointed out the error and the producer said, "A gun is a gun, who will know the difference?" I asked her if the local police watch her report. The head reporter jumped and said, "Change the graphic!"
Journalists are too lazy to truly do investigative journalism any more - they just feed short sound bytes about something then move on.
Journalists are not allowed to speak freely on some topics. For example, they cannot speak of regular folks using firearms for self defense - for fear of inspiring copycat 'vigilantes'. But they ARE allowed to talk all week about a school shooting - and inspire copycat school shooters.
Journalists try to be politically correct instead of honest.
The few honest journalists have their stations edit and sanitize their reports to make them more 'appealing' (politically correct), so the truth is obscured from the viewer.
Seriously, I do a fair amount of journalism work. I've seen the mainstream cameras pointed at things like this - but do they EVER report them on the news?