Run the fabric, inside out, under cold water to flush out as much of the ketchup/salsa as possible. Apply liquid laundry detergent to the stained area and let it soak in cold water for 15-30 minutes. Rinse the fabric with cold water. Next, sponge the stained area with white vinegar, applying the vinegar with a clean white cloth. Rinse with cold water, again. Pretreat the stain with a laundry prewash stain remover. Launder in the hottest water the fabric will allow to get out the stain.