I learned a hard and unfortunate lesson last weekend. I thought it would be good to wash the curtains in our living room. They've been hanging for two years now, so they are probably musty and such.
Here's the thing. I don't care if someone has spilled sour milk on my curtains. I'll never, ever wash them again.
If your curtains get nasty enough that they need to be washed, save yourself the trouble and buy new ones instead.
Or at least read the instruction label before you throw them in the dryer on hot. Oops.