A lot of us software engineers aren't exactly known for being social butterflies. Arrogance and crass behavior are more common than they should be, sadly.

"Before we wrap up, can I ask a few questions?"

(No interviewer, rude or otherwise, has turned this down on me)

"I just want to say this is as much as an interview for you to evaluate me, as it is for me to evaluate you. What do you think could have been improved in our interview for the future?" - if you feel they were especially rude/arrogant: "Do you feel you have conducted this interview professionally?"