[Paul]

I'm gonna go out on a limb here and say the reason why red shift doesn't visibly occur is because black holes are stationary and thus any matter that can, in any way, be pulled into their gravitational field already has (Note in all pictures of black holes they have a spherical vacuum area, not a trail). Seeing as black holes don't expand as things get sucked into them the black hole can suck nothing more in so the area is devoid of colour and light because it is devoid of matter. Each piece of orbital rock picked up by the hole would certainly not be big enough to change the colour of the vacuum but instead appear as a red blip for a fraction of a second before it is engulfed.

Now i wait for BM to prove me wrong .
Any amount of dedicated research > Wikipedia.

Wikipedia > You