Now I soak my fabrics in hot water for at least 20 minutes before washing them. And agitate the fabric by hand every so often.
If the water turns color, it gets another soak.
My kitchen is quite the sight when I bring home a bunch of new fabrics. Every kettle, large bowl, and the sink has fabric soaking in it.
I only put like colors in one container - so if there is a stinker, it won't cause any damage to the other pieces.