For example, an easy test scene…
If you create a plane and put a vray light above it, with GI on, and you exclude the plane from the Vraylight, you will still get some light on the plane. This is probably only true with higher multipliers, because the effect is less than if you included the plane in the light.
If you turn off GI the problem is not there. Its almost like the plane is still generating GI based off of the light, and then receiving it back again. Not Good!!
Using Max Design 2010 and Vray SP4