I paint EVERY tank black on the back now. Started a few years ago. I only ever want black backgrounds on my tanks, regardless of what kind of set up it is. For the last 25 years I used the plastic tank backgrounds, then switched to using black fabric...but over time they ALWAYS got stuff between the glass and background, or water stains were visible...and once you have a 100+ gallon tank in place against a wall, there's zero chance I'm moving it every few months just to fix the back. So I started painting the backs before I set up any tank a couple years ago and I'll never go back. SO MUCH BETTER. Looks WAY better than anything stuck to the back and never gets grimy. From my 1.5gal betta cubes to my 8ft long cichld tank - literally every tank I own gets painted as part of my set up process. I was sort of concerned ay the beginning about how it would affect resale if I ever needed to sell a tank, but it's never been a problem.
