> For example, "offset" generally only has the desired effect on a primitive shape.

It might not have the expected effect but surely it has a well-defined effect?

I've tried to get my head round distance functions whilst tinkering with raymarching shaders and the guru's over on Shadertoy and pouet.net seem to have a fairly solid understanding of which transforms behave nicely and which don't. They bandy around terms like lipschitz continuity which leads me to believe they've got a deeper grasp of this stuff than I have ;-)

I guess I'm saying that I have a hunch there is a fairly clear distinction between "things that keep the functions well behaved" and "things that don't"