cubemaps and nonreflective surfaces

Do cubemaps have an effect on nonreflective surfaces? I ask because I
was having a hard time getting lighting in my map to look good,
shadows, props being overlit etc, and I threw in a cubemap entity and
whalah. So whats the deal there? A happy coincidence? Does the
buildcubemaps do more than just build the cubemaps?

Thanks in advance,

***EDIT***

Crap this was accidentally posted in HL1 section of the forums. Admin pls move, I have no clue how to

cubemaps affect EVERY surface except prop surfaces. Since they help sort out lighting and stuff. Cubemaps are very necessary for HL2 maps. Place one for every good-sized surface you have.

one for every surface? I was under the impression you only needed one for each area of contrasting light.

Cubemaps affect props, yes. Basically, most shaders in HL2 use cubemaps
in some way or another. JFry is right, place one for each general area
that contrasts with another. In a few isolated instances, you'll want
to define cubemaps for specific surfaces, but most of the time no.

place one for each general area
that contrasts with another.

How do you mean exactly? One per each room? Or if I have a fancy
lighting effect at one end of a large room will placing two cubemaps on
either end of that room cause the effect of the lighting to be
different on the far side (and if so, more lit or less lit according to
the other side of the room)?

I realize I can play with this on my own but I have done a lot of playing and not a lot of sense is coming of it :sad:

One per each room? Or if I have a fancy
lighting effect at one end of a large room will placing two cubemaps on
either end of that room...

Exactly correct. That's how I use them. The lighting effect
on the walls and models looks much better with cubemaps built.