It's also useful to consider how often real life resembles the prisoner's dilemma, iterated or otherwise (in my experience, not often) and in the cases where it

It's also useful to consider how often real life resembles the prisoner's dilemma, iterated or otherwise (in my experience, not often) and in the cases where it appears to, whether other factors (such as getting the reputation of being a dick) might swamp the advantage that is to be gained by betraying your partner. Of course you can always cook up a situation where any strategy is the best one; but in my real-life experience kindness tends to be a pretty good strategy, for a variety of realistic objective functions. (edit: grammar)