This book was probably published between 1942-1965. It was about a family that lived near train tracks so that the soot covered everything in the house, including the family. The doctor was sent for and I remember he looked everything over and said, “Hmmmmm” which I thought was funny as a small child. The illustration I remember was of a pig sleeping in an open dresser drawer. I seem to recall the illustrations were not in color but more like sketches. I have searched for this book for 10+ years. Nobody has ever heard of it.
Also, if this helps, my mother belonged to something called the Junior Literary Guild and many of my books as a child were JLG books. Maybe this one was as well. My older siblings thought the book was called The Dirty Family or the Dirty Little Pig or that “dirty” was a part of the title.