I'll be more specific by citing a random example which is more or less typical of newspapers:
A few years ago there was a woman in America who became famous for her protests of the U.S. war in Iraq. A great many stories were printed about her and I read many articles describing her background. Often, these articles contained a significant error in reprinting her erroneous claim that she belonged to a particular non-partisan organization (American Gold Star Mothers Inc) that is well respected and goes back to before World War II. She did not belong to that group but founded a politically based group of her own that had a nearly identical name.
Whenever any story appears online (whether it originated in a newspaper, in broadcast or elsewhere) it is nearly instantaneously linked to by thousands of discussion forums and millions of sites. Eager participants can't wait to fact check every tidbit and want to be the first one to catch the original source making a mistake. I remember quite a few newspaper journalists printed the protest woman's false affiliation with the Gold Star organization and they were inundated with complaints to run corrections. The fact is, the journalists who ran the flawed stories were not adequately fact checking and they could have easily discovered their error had they simply taken a few minutes to go to the Gold Star web site and read a statement they had put up regarding that very issue.
This type of error is a common occurrence, and traditional journalists often take shortcuts and assume that re-quotes are accurate and that statements made to them by persons they are interviewing are factually correct. Reporters used to do a much better job at this but for whatever reason, this has become less of a priority. I could provide countless examples of this, limited only by my willingness to sit at my computer and type.
Of course, this happens online as well, but I'm not comparing the average quality of journalism online versus traditional journalism (online would easily lose in that category). I'm comparing the highs and the lows. The quality of traditional journalism, including newspapers, tends to stick pretty close to the average, and it never gets much worse or much better than barely mediocre. Online journalism is all over the place; from the most tin foil hat wearing, rambling garbage to the highest quality, most objective, extensively researched and cross-referenced information.
I've found that if you want the highest quality, you need to seek it out online but be prepared to do a lot of weeding.