I am pretty much the same way, which is why I never did good with small talk that is so prevalent. I do have a guard up, but not sure I consider that the same thing. I make sure of people and their worthiness to certain considerations before extending them. I never felt that everyone is owed respect. I will agree with politeness till proven different, but to me respect is something one earns.
What's the point? It's more work to do all of that, and in the end, not enough benefit.
I couldn't have said it better myself. Thanks for weighing in.