Over the years of making my own laundry soap I learned that "Dingy" happens when you use more soap than is necessary to get the clothes clean and don't get all the soap scum out. As DeeAnna mentioned,
"The fabric will look yellow and feel stiff and harsh."
No one has yet mentioned the importance of adding white vinegar to the rinse cycle. (This is also a great practice to extend the life of your machine.
) I sometimes run more than one rinse cycle to be sure there's no soap left in the clothes. I can tell by touch whether the clothes are ready to go in the dryer. And, I just love folding clothes out of the dryer... so soft, and smell so clean... I really do!
My laundry soap of choice is 100% coconut oil LS, 2:1
water to lye ratio; 0%
SF; 40%:60%
soap to water for dilution.
I use OxyClean and sometimes 20 Mule Team Borax or Liquid Calgon (both water softeners) for an extra boost.