A way to test fabric for stains

Has anyone found a way to test fabrics for stains? I would like to know  if a fabric will stain over the course of a day before I use it to make clothes 

I know some of us gently rub the fabric on the sole of the doll's foot to see if any color will transfer. Even if it does, it's in a place that is less visible and you can work on cleaning it off without having to see it all the time. Might also be a good idea to purchase extra hands or feet if you are against testing on your doll.

Hope this helps! 

I would probably use spare parts as well.

When I received a mildly stained body previously I was able to remove it by using coats of Oxy, which is an acne cream.