I'd like to second that opinion on the harsh side effects of dyeing. When using RIT dye the combination of the hot water and salt really takes its toll. I try to do all of my dying in one go to try and minimize exposure. I have the best success in dying a lighter material another darker color. Also I only use dye when I have multiples of a item just in case, well in case things go horribly wrong.
I think the worst experience I had dyeing items was when I tried to dye the BBI Chuck Morris flightsuit. I tried to use RIT color remover to lighten them up but it made them turn an pale yellowish-orange color in the dye bath. When I removed them and rinsed them out they immediately changed back to their original green color. In the end I had to bleach them out and then dye them to the appropriate color using Black RIT dye because it was the only color that would take.