Well you only lose 1 point when they don't like it, and you can gain affection from conversations that don't affect your light side dark side points. So just try to answer those ones in ways that your companion would like and give gifts, then the minor amount of affection you lose from getting dark/light side points will be rather insignificant.
---------- Post added 2011-12-08 at 11:56 PM ----------
Bioware does this with all their games for some reason. It's like there will be a serious moment and they need to keep the dialogue serious, but they'll make the text you choose silly to keep it light. I've always thought they probably have different people writing the text choices than the people writing the dialogue and those text writers like to be silly. Would be a good question to ask at some type of Biocon.