Unscrupulous editors happen anywhere, in any publication, and Wiki, for obvious reasons, is wide open for such transgressions. In September of last year, for example, hundreds of “black hat” English Wikipedia accounts were blocked following investigation, according to WIKIMEDIA blog.
Wikipedia is now equipped with tools to parse its articles for bad edits. See Artificial intelligence service gives Wikipedians ‘X-ray specs’ to see through bad edits.
If you don’t know yet but curious enough to know what are the most edited Wikipedia articles throughout its 15 year history, click on either one of the two links below.