As a collector, I'm not much of a fan of the red PS3 cases because it means I'm not getting an original print of the game. I also do think they're ugly, but that could be an unconscious reaction to the color because I know it's not original.
Also, a lot of the different colored cases for greatest hits games also results in modified box art that's not usually very nice. The Platinum Hits on the 360 spring to mind in particular.
Of course, I understand the value in the practice. Publishers do this in an attempt to make it stand out from the other games on the shelf as something special, but the result often seems tacky to me.