I wonder if the plastic breaks down and the stain gets enmeshed somehow. I had a clear glass coffee cup that kept getting coffee stains and it was textured. Someone suggested to me that the stain was seeping into the design. As an aside, the textured glasses seem to be a good idea for elder people in terms of grip.
In response Fight_for_Life to her Publication
Any plastic you microwave will be ruined and set tomato stains in it. Stainless steel for any tomato base food.
