Overall it doesn't matter to me as long as that person has an open mind and is willing to admit they're wrong sometimes, within reason of the subject. I generally just don't bother with known racists/homophobes/extremely religious folks, but if I didn't know that about someone I consider a friend and I find out in casual conversation I do confront them on it. I don't expect to bend minds and know that I'm not right all of the time, I just want to know I'm being considered and someone with a closed mind won't hear you. Some of my best discussions have been with people who had opposing views on religion and politics simply because we didn't immediately shut each other out after realizing the differences.