I work with a HUGE charity quilting group in Phoenix associated with a church. We get all sorts of weird things people think would be ok in quilts. Families just do not always understand quilts. Seriously---fiberglass curtains? lol
We would never try to wash a top. If it is nasty---we just toss it. That being said we have many many tops waiting for quilting. Our members often make tops and then hope one of the few long arm quilters will quilt them.
Goodwill here sells fabric stuff by the pound to some factory type recycle place. These nasty things get put in a plastic bag and labeled as such.
We have a big presentation program once a year for recipients. I sometimes worry about pet hair and the recipient as they do not require the quilts to be washed before presenting unlike Quilts For Kids.