Given that I garden with such an active colony of carpenter bees, I've become an amateur witness to their behavior. They're fun to photograph, or try, because of their lumbering and hovering (and no stinging).
Carpenter bees are known to some as nectar robbers. When the flower has a deep corolla, they break the sides to "steal" the nectar, technically without trading their pollinating services. That's what makes them thieves, but then there's argument on this point.