What's the worst thing that can accidentally go in the washing machine with your washing?

I was doing laundry at an apartment laundromat one time and when I took my clothes out of the dryer they all had little spots of colors all over them in various colors. The lady that cleaned the laundry was there and told me it looked like bits of colored chalk had been thrown into the machine, and she gave me a bottle of Goo-Goo, I had to treat each spot & rewash but it took all the colors off.