All the time.

Generally I only remember the cause of my dispositions if I feel it's important in itself. In the case of something like political beliefs I have a commitment to throwing out anything I can't justify through verbal reasoning and reference to fundamental values. With likes and dislikes - from those fundamental values to flavors of ice cream - I don't consider the path that got me there particularly important.

Sometimes I need the justification for ulterior or social reasons. It doesn't particularly matter to me why I like the people I happen to like, but I try to examine them at least enough that I can give them substantive compliments when appropriate, even if this examination doesn't come naturally to me. Cynically, most "debate topics" are like this - you need the justificatory reasoning in order to engage in cocktail conversations.