I feel I can hold an intelligent and civil conversation regardless of their idiotic ideas about anything expressed on a bumper sticker. You don't have to agree with everyone to be social and courteous. Being able to interact with those you do not agree with in a civil manner is a mark of good character. If you cannot converse with those who have divergent opinions than you do, you are pretty shallow bordering on ignorant.
But you must admit it's handy when they announce which topics you should avoid. ;)