Easy, ask them what they mean. I like the idea of airtight.

Try and find someone who likes the sense of power it gives them, rather than someone who just likes to hurt you. Always have a safe word which is like the emergency stop button.

Dont get involved with anyone with BO.

Try and watch a film about it and see how he reacts, if he smiles when he is watching you are half way there, if he gets a set jaw, leave.