Use it all the time. I'm a prewasher though for SEVERAL reasons.

I use muslin especially on a embrodery quilt that is mostly white/off white. It also works great for background on some quilt tops too. I do LAQ and some customers still want only muslin. It is really a personnel choice, but there is nothing wrong with what you do.

I use it on mostly everything. I am retired and love to make quilts and I am perfectly fine with spending my hard earned money on the front that everybody sees. I even buy whole bots in a wide width and cut off from there. Very little need to piece the backing. I also like that it is ripable and I can square it up easily for the LAQ.

I use muslin to back almost all of my quilts, I really don't care if it's "boring" or not according to some folks. :-)

I mostly use bleached white, and I am really getting into dyeing the muslin for backing. In fact, I just did a grey dye for a backing on the quilt I'm trying to get finished for my husband. He loves it because it's unique, and I love it because I bought the high quality muslin from JoAnn's when I had a 50% coupon, plus a 15% off on total purchase coupon. I have a beautiful, totally unique backing that is 120" wide for which I paid less than $20. No piecing involved, and I think it's far from boring!

I have using unbleached cotton muslim for the backing of all my quilts, since I began quilting in 1995.
Although modern designer backings seem to be gaining more popularity, I love to work with the unbleached
cotton fabric, which is often sold double- width, (which can be a welcome saving if you have to limit your budget).
Don't forget to wash this fabric before using it, to get rid of chemicals and starch which is often added. This will
also deal with any shrinkage. I set this fabric in my washmachine for about 1/2 hour, using only hot water.
That's all you need. After some ironing, your muslim fabric will turn out soft as butter and ready to use as
backing. I find it ideal for hand quilting.

My childrens favorite quilts have muslin on the back.

Also on ebay a long arm quilter uses it for backing.

I do hand dyed fabrics- I use it all the time.

If you decide not to use it-let me know. I may take it off your hands. LOL

I like Muslin, when wshed it is so soft and it makes a wonderful backing for a quilt. If you are making a scrappy quilt or applique blocks on Muslin it looks great on the back. I would use it if I were you. Wish I had it I would use it and also I am getting ready to make a Christmas Quilt out of embroideried blocks on Muslin, that would work out great fro me. Use it and be glad you have it. Sorry for any loss you had with Hurricane Sandy.

I use it a lot as backing. There are as many ways to make a quilt, as there are quilter's to make them...there are no real "Rules"...that's how I feel about quilts I will use or gift. If I were to do a quilt for a customer, then the customer would decide what to use...and if for a show...I'd probably use a fabric that was complementary to the quilt top.
I still buy muslin by the bolt...usually 108" wide.

I'd preshrink first but I'd use it. Yes there is prettier backing fabrics out there but their not free. I know many of us who have used muslin backing and were happy with the results. It will give your quilt a vintage feeling.
I really can't imagine what you all went through with hurricane Sandy. All one can hope is that each day gets better.

I always use muslin for backings.