The Component function getDesktopScaleFactor() is not returning the correct scale on Retina displays. It returns 1 instead of 2.
The reason I stumbled upon this is I'm using proxy components with the ComponentAnimator. I was trying to figure out why all of my animations were blurry when using a Retina display. Turns out Juce was taking half-sized component screenshots, then scaling them to fill the space :).