Soap-like fabric softeners coat laundry with a waxy lubricant that lets the fibers slide past each other, reducing wrinkling and smoothing scratchiness. They also make napped fibers stand on end for fluffiness and reduce static cling caused by tumbling in the dryer.  Over time, the waxy coating can create a dingy look and reduce absorbency in towels and sports fabrics designed to wick moisture. For whiter whites and brighter colors, use a high-performance laundry detergent (like we use every day) and skip the softener.