Removing stains from absorbent fabrics is much easier than from non-absorbent fabrics.  Synthetic fibers are tough to stain but hard to clean once they're stained, whereas natural fibers are easy to stain but easy to clean. So even though cotton is prone to staining, you can usually clean it easily. By contrast, oily stains on synthetic fibers can be tough to remove. You may need to use dry cleaning solvents or pre-treatment products like Zout Laundry Stain Remover or Resolve Spray 'n Wash Pre-Treat Stain Remover to clean the fabric.