Aluminum foil is approx 55% reflective. German aluminum can be 95% reflective. The pebbled surface does indeed help to make a more even distribution of light. It doesn't get very hot under my 600w hps with german aluminum reflector because I cool my hood. Of course if I didn't cool my hood it would get hotter under there, because as you said aluminum reflects heat, which is the point. With aluminum foil you only reflect 55% of the light, and over 90% of the heat. With german aluminum you reflect the heat and light equally. It's not BS. It's fact, and you are misinformed.
Heh heh, I expected this......
I'm not here to debate you, I'm here to inform you.
I think you should know, I worked in an optical lab for several years.
I know all about light reflection and refraction, etc., etc.
The information you've been told is incorrect.
Those dimples you're referring to are concave surfaces.
Concave surfaces focus light into pinpoints.
When there's hundreds of concave surfaces receiving light from many different angles, any light reflected gets scattered as focused beams in all different directions.
This is NOT the same as diffusing the light.
In fact, it's wasting usable light because it's being scattered away from it's intended target.
You've been had. You've fallen for a gimmick. You reflector is LESS efficient than a similar sized non-dimpled reflector.
I wouldn't get too upset over it, it happens to the best of us.