Can Wikipedia be trusted?

In my opinion Wikipedia cannot be trusted as a source for any kind of information. Although Virgil Griffith created a "Wikipedia Scanner", people can still log on from a proxy IP address and change information. I believe that too many students, elementary to college level, depend on the internet for information, but that is how are society is today. In order to get accurate and true information, someone needs to either look it up in a book or find an internet site that is secure and not open to the public. Throughout my education, I know I have been tempted to use Wikipedia as a source, but my teachers made it clear that it is not an accountable source. I believe that every teacher should banned the use of Wikipedia as a source when gather information for a research paper, project, class dicussion, etc. Even though looking for information on Wikipedia is easy, it may not always be helpful.