Wash or not wash

One of my friends was getting a back ready to put on her quilt and asked me if I thought she should wash it first. It was a dark teal batik and I suggested washing it. Four washes , one with vinigar and it is still bleeding. She, of course was very upset. Now, not wanting to ruin the quilt, she bought a different material for the backing. Then, called the quilt shop where she had purchased it and told them the story. The clerk said she could not take back any fabric that had been washed and told her that quilters do not wash before use. She called me and wanted to know if I knew other quilters that washed their fabric. I do know many that do and some that don't. I decided that this would make a great topic for discussion. I, personally do not always wash. But I have also had one bad experience also. Thanks for the input. Marci