I ask because recently Colonel Will and his friends have been joining several MP games (they usually pick ones where no one is currently playing so that they are the only ones online) and then rehaul parts of the map that they consider need fixing.

To be honest I found this very educational to ...

Is it considered griefing if one enters a server and changes things around because they feel it isn't correct? For example, if I enter a map and start removing every roundabout and loop I see because I feel that roundabouts and loops are bad?