I am not completely opposed to unnatural fish, e.g. flowerhorns. Though I find them ugly. And I don't want to see them getting out in the wild.
That said, if I'm buying a convict, I want it to be a convict. Or a yellow lab, to be a yellow lab. Or a....the list goes on. I won't buy from the 'mixed african' tanks at pet shops.
I also try not to mix species that will cross. Or at least minimize the risk - make sure I have matched pairs (for CA/SA cichlids) and/or a good male/female ratio of Africans.
As far as buying fish that 'look good', I've personally leaned more toward fish with interesting patterns (various loaches, oddballs, etc) to satisfy that urge.