Flat paint (even black) can still be somewhat reflective. Black fabrics do a much better job of absorbing light around the screen. Most of the theaters I design have the entire screen wall construction covered with black GoM wrapped panels. The effect is the whole screen wall dissapears and it looks like the image is floating in the middle of space when the movie comes up. Fancy woodwork is nice but I can't stand any reflections up front when I'm into a movie.
This is my personal HT. Everything looks deep black except the screen here. I know, I know, I still need to do my acoustic panels on the side walls and door. Your personal projects always come last, but it's on my to do list
Up close with the flash on you can see there is actually a big difference between the black fabric and the black screenframe material. And the paint color for that matter:
Same camera settings, just step back a few feet and it all goes very black
This is with the camera set on the back of one of my front seats, the front wall completely goes away when movies etc are playing, important for the suspension of disbelief:
COD 4, my current vice:
Might as well throw in some 18" inch woofer pR0n while I'm at it:
In the end I think the most important thing is what you see(or rather you don't see) when then movie is playing. I find any reflections around the image to be extremely distracting.