Hi guys! All my tanks are tinted at the sides and back. Next time i do it, i might include the floor as well. I used a certain black type which does not allow you to see through. perfect background. this works best if your tank is new as they dont have stains or scratches yet that might look ugly. (Though i also did it to my 15gal grow out.)
IMO, better than paint coz its easy to install (though you might need an assistant if your tank is longer than your arm span.)
it would'nt chip off like paint.
Easy to remove/peel-off in case you wanna change color in the future. using a razor to flake off paint may scratch your tank.
Plus, you eliminate the possibility of having uneven spots.
Pics...