It's not trustworthy, and that's not just because there are people out there putting in false information, such as implicating journalists in presidential assassinations and claiming such and such senator married his right hand.
There are a lot of people out there with misconceptions about certain topics and they don't even realize they're enshrining their mistakes into Wikipedia. Maybe common misconceptions have been rooted out of Wikipedia, but what happens if you have a misconception, type it into a Wikipedia article and no one else edits that article in months?
It's true some articles have lots of citations. But who checks those citations really back up what the article is saying? For example, there might be the statement "Charles Darwin was gay," but when you actually look at footnote 3, it's a newspaper op-ed piece that mentions neither Darwin nor gays. It's worse when a footnote points to a 40-page essay in an academic journal but doesn't tell you the page number where you will actually find the statement that supposedly backs up what Wikipedia says. Do you have time to read a 40-page academic journal article to find the one page in it relevant to the topic?
Then there is correct information that is kept out of Wikipedia. To gain any power on Wikipedia, you must engage in some very dirty smear tactics against your opponents. It gets to a point that the factual accuracy of any statement is completely irrelevant: if it was added by your enemy, it must be deleted, and your enemy denounced as a vandal, a troll, a sock, a score-settler, or whatever idiotic insults Wikipedia's keyboard warriors can manage. Also, the information itself can be insulted as being non-notable, cruft, POV, spam, etc.
The end result is that each Wikipedia article is a mixture of true facts, misconceptions, and subtle falsehoods, and some relevant facts get left out. When you want to know everything there is to know about a given topic, Wikipedia is the last place you should look.