I do even if i already have my mind made up. It opens up discussions and expands on ideas. So yeah, its fun and entertaining. I like getting a rise out of people, pro at pushing buttons. I think it gives me a better scope figuring out who people are, their motivations/agendas and intentions.
Oh I do this endlessly. But only if it is something I don't already have a strong opinion on. If someone challenges my strongly held belief or value I will fight on that side. Although I usually am still open to hearing other people's opinions on the matter so long as they don't get too personal, in which case I can be a bit defensive!