"Detuning refers to the subtle massaging of an edge's sharpness or base bevel near tips and tails to intentionally adjust performance of a ski or board. On traditional skis, detuning behind the contact points makes a skis less grabby and "hooky" for easier control. But detuning a shaped ski can be real bad news. It makes the ski more "nervous" due to shortening the effective running surface, plus the skis won't initiate turns as desired due to the decreased radius and running surface."
I am not a good enough skier or ski on really good snow to really notice a big difference, but I've definitely noticed catchy edges after beveling