Trolls have infiltrated wikipedia:
| Sneaky vandalism |
Vandalism that is harder to spot, or that otherwise circumvents detection. This can include adding plausible misinformation to articles, (e.g. minor alteration of facts or additions of plausible-sounding hoaxes), hiding vandalism (e.g. by making two bad edits and only reverting one), using two or more different accounts and/or IP addresses at a time to vandalize, abuse of maintenance and deletion templates, or reverting legitimate edits with the intent of hindering the improvement of pages. Some vandals even follow their vandalism with an edit that states "rv vandalism" in the edit summary in order to give the appearance the vandalism was reverted. |
http://en.wikipedia.org/wiki/Wikipedia:Vandalism