Actually, yes. On many occasions, I've read Wikipedia articles about
things that I know about, and some of the information that presented
itself as fact was opinion. There is a mechanism by which you can mark
suspicious "facts" as opinions, but that mechanism wasn't always used.
I don't fault Wikipedia's inaccuracy; I fault them for masquerading as
purely factual while there's no editorial control over published
opinions.
The sources of information that I used in all of these cases was my
past experience about fields in which I have sufficient expertise. For
instance, MSDN isn't always correct, but if I've written a working line
of code a dozen times, I know what works.
As stated, I don't use Wikipedia for subjects that I don't know enough
about to discern fact from opinion. Since the 90% of my need for
Wikipedia is to learn things in areas where I don't know enough to
discern fact from opinion, I consider it unreliable.
I regard all sources similarly, and any web site gets the same
scrutiny. If a web site isn't properly sourced and doesn't contain a
line of reasoning that makes sense to me, I consider it unreliable. My
gripe with Wikipedia is that it informally (and occasionally formally)
presents itself as more authoritative than the rest of the Internet,
while it truly isn't.
If everyone used the standards for qualifying information that I do,
there would be no problem. I'm also not trying to convince anyone to
believe me. My friends and peers have listened to my case against
Wikipedia and none of them use it anymore, some because of my argument.
Clearly, I'm not going to change the world by posting on
microsoft.public.dotnet.languages.csharp. I'm simply stating my opinion
that Wikipedia is dangerous to the unsuspecting masses.
Stephan