My mother always claimed that quilts couldn't be washed (at least the way her family made them?). She said the (cotton) batting would bunch up and you'd end up with this lumpy thing that had no insulating value in one spot and a bunched up batting that would get compacted and wouldn't keep you warm where the lumps were either.
Maybe, as I alluded to in the first paragraph, this had to do with the way her people made them. They sewed what we called "quilt covers" which would have the patchwork on top and a full piece on the bottom. They'd put the bottom piece on the clean floor, lay on the cotton bat, then hand sew the edges together. Then every 8 or so inches, they'd take a piece of yarn about 3" long and run it through and back up through the bottom and top covers and tie a granny knot in the yarn. There was no stitching through the quilt except around the outer edge and these yarn knots held the bottom cover, the batting and the patchwork top in place. I suspect a lot of quilts in other families got more substantial stitching throughout the quilt.
To keep them clean, you ALWAYS slept with the top sheet folded back over the quilt and the bedspread covered the quilt and the sheet so you only drooled on the bedspread and the pillow case at night. Of course with a bedspread layed over everything, this sort of defeated the idea of showing off the quilt pattern since it was hidden all the time. Then again, you never, NEVER, EVER entertained friends or relations in your bedroom. That section was basically off limits except for piling coats, caps and hats on when company came over. So once in use, the quilts were never to be seen again. Come warm weather, the quilts got packed away in a cedar closet or cedar lined chest.
I have a couple of quilts made by my mother and grandmother and Grandma's sisters. One's a "Friendship Quilt" where the neighborhood women got together and signed their names each on an individual patch. It was made up around 1919 or 20 when my Mom's family left Southwestern Minnesota to move up north of Minneapolis.