Aside from the obvious poor sportsmanship and poor ethical gaming choices, what is to prevent a player from joining a faction with the sole purpose of causing havoc on the same color. They would be effectually playing for the opposing faction in spirit, though not according to the scanner.
Do the terms of service ban this type of action? Or is it just evil?
Best Answer
If the player has a second account on the other faction, then they would be violating the Terms of Service.
However, if it is their only account, there are no rules to prevent them from playing how they want to play. There's also no way to verify that a user's sole purpose is to "watch the world burn" unless they explicitly say so (and even that could be sarcasm).
Still, feel free to report any players that you feel may be double agents. Chances are they have a second account and if you can raise enough suspicion, Niantic may investigate your case.