I think that courtesy and proper etiquette are tell-tale signs of intelligence: if you are a “good person” you should be courteous. If you are an evil guy, you should be polite at least to fool other people. The most selfish guy wants to behave correctly if he is a bit intelligent since he can squeeze the most out of people. Lousy etiquette is never a reasonable proposition in my book, whatever your objective.
What I did not realise until recently is that you can read predisposition to team play from behaviour: that was clear to me when a person in my organisation acted rudely towards me when there was no necessity for it.
Point is: if you misbehave towards people even in your own organisation, how can you be a team player? How can it be said that you are willing to act toward a common goal? More probably, it is a sign of destructive competition in an environment where everybody should be supporting each other.
Until next time, if you want to be a good team player and a decent human being, act appropriately and help create a favourable environment for everyone.