I'd say they do or die. Most brownies I have got have turned into some of my favorites. You just have to develope an eye for the diamonds in the rough, and be willing to have patience to let them bloom.
Some of the beauties I have polished would include, a "GARF" like Bonsi, "Jedi mind trick" Monti, purple cyphastrea, Ice blue Stag (once orange with red bugs), mystic sunset monti, and a few stunning lokani and granulosa pieces.
If you take care of it and have patience you can't go wrong with the brown bin at the LFS (as long as you QT in before).