I, for one, won't be pissed if my opponent plays tengen against me: I might even be at a loss as to how to play properly against it. On the other hand, I
WOULD be pissed if my opponent had a problem with me playing tengen against him, and would find
HIM disrespectful towards me.
That being said, I would totally be pissed if my opponent played his first move at the 1-1 point (unless he's a total beginner, obviously

), because then I would know
FOR SURE that he's messing with me

... or that he misclicked!

I once opened on 2-3 due to a misclick- I'd intended to open on 3-3. But I won the game anyway and my opponent accused me of being a jerk afterwards. It's just because I hate asking for undos.