Have to say I agree with Kaz and Seagul - the actual show it self was well made and warts and all. However, your comments regarding the american swingers were well condescending and not called for.
Nothing to stop you having those observations and as has been said by others, they maybe should have been kept under wraps. The comment about having sex with your Grandad was way off. The guy was there, like you, to have fun, and if that is his bag then good on the bloke for getting out and doing it at his age, if it wasn't your thing you be firm but polite and move along.
My opinion is, is that you were too eager to get down to things and came across as very arrogant, I am not saying you are, that is how it appeared to me.
If you both just chilled a little maybe be less eager then things would have been easier for you.
My thoughts anyway.