Why does a 3D model look correct but fail when using SUBTRACT?

[indiancad]

Have you ever had two solids that clearly intersect, but SUBTRACT doesn't produce the expected result?

One thing I check is whether the solids actually overlap in 3D. They may appear to intersect from the current view while only touching or being separated along another axis.

Using 3DORBIT to inspect the intersection from different angles usually makes the problem obvious.

Have you ever found that two solids only appeared to intersect because of the viewing angle?