The red uakari is just asking to be misunderstood. They've got hardly any tail to speak of, so one might assume them to be ungainly in their arboreal homes. But that's not so; their long arms and legs make them as dexterous as any other monkey.
And what about that red face? No, he isn't angry. Quite the opposite: he's healthy and happy. Healthy, because it is presumed that the bright red face is meant to display health, as opposed to those afflicted with malaria, who tend to take on a pale countenance. Happy because this particular monkey is the nicest monkey in Peru. A real charmer, despite looking very much like a zit I had when I was fourteen. source