The construction of a picnic bag will determine how to clean it. You should clean wicker baskets with more care than insulated coolers. You should always follow the care instructions that came with your picnic basket. You can spot clean insulated cooler picnic baskets with warm soapy water. To remove stubborn spots you can scrub the area with a toothbrush. Wicker baskets can be fragile and will break if left to dry out. Use a microfiber cloth to wipe down the wicker. You can also dampen the microfiber cloth using warm soapy water (use mild dish detergent) to clean it. Before using, let it air dry. To restore moisture to the wicker, use either a wood conditioner oil or cutting board oil.