Scrap quilts seem to come together and look fabulous. I think it is the play between dark, medium, and light values.
I have some friends who give me their scraps. Which I really appreciate. Anyway - when I show the quilts that are made they often search the tops for their fabrics. They really get a thrill to know the fabric has been used - from something they wouldn't work with any more - into something fabulous. They often talk about the stories of the original quilt. I feel like I am maintaining some long unspoken quilting tradition/mystery.
Oh for me "scraps" are any left over fabric from previous projects (mine or others) where there isn't enough to use in a "co-ordinated/planned" top.