I agree with Oohfeeshy. When I was getting Orion and Draco, all of the bettas looked pretty healthy. Some were more active than others, but that could just be personality differences. When I went back a week later, I saw a couple that had been there before, including a blackish/blue one that had the curling fins and looked to have fin rot. I felt really rotten, he was one of the ones I had looked at, but I didn't really wish I could go back and exchange the guys I have now, it could just as well have been one of them there with the fin rot or else dying in some "betta bowl" the size of a wine goblet. Most of those "healthy" bettas are bound for death and misery too. Perhaps if you had taken the other one, it'd now be one your boys sitting there on death's door, sick and shredded. So I don't think you, or anyone really, should ever feel guilty for choosing a fish based on pleasing looks. In a pet store situation, it's probably a darn good chance that you're rescuing it from a horrible life.
I admit, I particularly wanted to find healthy fish after my ordeal with Haiku. I'm new to all this, and I NEEDED success or I'd just have gotten very discouraged. I think it's admirable to save ones in immediate need, but I think it's natural for people to choose ones that look healthy. When people are picking out a flower or plant at a nursery, they tend to pick one pleasing to the eye and even more, one that is healthy looking. I'm not equating the life of a fish to that of a plant (though to some, they probably are equal), but I just think it's natural for people, especially if new to caring for something, to pick something they have the most chance of success with. Yes your Six or Charlie may have been purchased by someone else, but they very well could have ended up in some vase with a plant, one of those stupid bubble purses, or some other atrocious device like that candle bowl.
Yeah for Grulla!! It brought tears to my eyes thinking about that poor little sick fellow and being too far away to help. 
