In many ways we are now so dependent on Wikipedia that it is rude and unfair to criticize this great institution. Wikipedia is an order of magnitude better and more comprehensive than any encyclopedia in the past.
Nevertheless I run into problems with (the American version of )Wikipedia ,which I do in fields that I know very well, on occasion. When I run into these problems it is always because Wikipedia ends up having a Left-wing bias.
Of course we all grew up (if you are over 20) in a world where the default position for everything in knowledge and information and data was filled with a Lefty bias. But that has been changing thanks to the slow but steady growth of pro-commerce understanding that is most evident with the emergence of talk radio and Fox TV.
I can give you two examples so you know what I mean. Take a look at random legislature (sortition), a field in which I was the first to write and develop the material (there is a reference to my book). You will find that the wiki entry is a debate between the reasons for random selection of legislators and a few outliers who don't like it. This is a new idea and should be treated with respect and have a wiki entry of its own that completely explains what it is about. It is not the place for a rant by Lefties and status-quo-others to voice their opinions. The first quote in favor of random legislature is from a Marxist. The authors don't know enough to mention that the largest state in the world (California) used random selection to create the committee to design apportionment. It has been very sucessful and widely discussed.
The other place to look is: global warming. It is 95% standard Lefty rant and 5% questioning. When I looked yesterday there was no acknowlegement that the latest IPCC again reduced the predicted effects. And no mention of the pst 16 years with no warming.
Wiki needs a button to click if you know a great deal more than the people writing the wiki and wish someone to contact you. It also needs a button to click when a wiki entry is a decidedly filled with Left-wing bias. No other bias ever seems to stand out so blatantly.
(There is a more comprehensive article on the Lefty bias of wikipedia here. Don't waste your time looking at Wiki bias, they never noticed the six Lefty mainstream media channels in the U.S. versus the one channel that isn't Lefty. They also have an absurdly biased video on the influence of money.)