Really, there is no such thing as good or bad characters, you can get the same character y once treating it great and one time neglecting it. So don't worry if it's a godd or bad character, just play with it and have fun. ^^v
I believe that there are good and bad characters. I believe that there are certain ways to get specific characters.
It would be pointless to have discipline if it wouldn't affect what Tama you'll get! And the instruction booklet says that "Your Tamagotchi will grow depending how well you treat it."
I think these are the factors that will affect will you get a healthy or unhealtyhy/good or bad character: Hearts, discipline, games for happy hearts, parents etc.
And the "fact" that someone has got a "bad" character" by treating it well won't change my mind. I got a Mametchi when it's hearts dropped below 1, but I played for happiness and disciplined well.
And Tarakotchi isn't the worst/unhealthiest character!
So i think it would be soooo stupid if how you treat your Tama wouldn't affect what Tama you will get.