Mistakes in dyeing can be messy... but sometimes there is a happy outcome even when you think it is all going to crap partway through.
I made a measuring error while dyeing a violet/blue yarn and as the dye was already in a jar with water in it, I couldn't easily save it. I wanted to use this large volume of dye so it seemed the right moment to try some overdyeing.
A friend recently gave me quite a lot of churro yarn that was dyed by someone else. The colors weren't quite what she wanted and she asked if I could use it. And not being able to say no to free high-quality yarn even when the colors were a little bold, it came to live in my studio.