In one of the Panels from Hell, Sven took time to talk about how the cat is so good for stealth and sneaking, and "demonstrated" this by moving around with the cat and avoiding the sight cones of the enemies - something he could also have done with a 500 lb gorilla dressed in a one-man-band kit and playing for all it was worth, equally effectively and with equal ease.
They don't posess any particular or unique sneaking abilities above or beyond anything and everything else.
