Rick, to answer your question, yes! Except for when you're driving west on Thursdays, and then the answer would be 'seven'.

My standard reaction in cases when I'm not sure if a statement's made ironically is to play along and respond literally. Sometimes I escalate the irony to see what happens. You don't hurt anyone's feelings by not taking them seriously, but if they DID mean to be ironic, I can have the same claim of "you didn't get it" that they have. It's a wimp's way, but it's mine.

Casual Observer, I believe using irony wouldn't have been much of a problem in letters because people generally wrote to people they knew. They'd know what to expect.