Running already dry clothes through the dryer is generally safe and won't ruin the clothes. Dryers are designed to tumble and heat clothes to remove moisture, so they can handle dry garments without causing any significant harm. In fact, some people use the dryer for a short cycle to freshen up clothes that have been sitting in a closet for a while and may have a slightly stale smell.
However, keep in mind a few considerations:
Energy Efficiency: Running the dryer when it's not necessary wastes energy, so it's best to avoid doing this unless there's a specific reason, like refreshing clothes.
Fabric Sensitivity: Delicate fabrics, such as silk or certain types of lace, might still be susceptible to damage from the heat and tumbling, even if they are already dry. It's always good to check clothing care labels and use low-heat settings for delicate items.
Wrinkles: Tumbling dry clothes that have already been ironed or are wrinkle-free might lead to some creasing or wrinkling. It's usually best to avoid unnecessary tumble drying for garments that you want to keep wrinkle-free.
Utility Items: Items like towels, kitchen cloths, or cleaning rags that are already dry can be safely dried again if they need fluffing or if you want to ensure they are free from any remaining moisture.
In general, running dry clothes through the dryer occasionally won't have a significant impact on their lifespan or quality, but it's best to use the dryer efficiently and only when necessary. If you are concerned about any specific clothing items, always check the care instructions and use appropriate settings on your dryer to maintain the best condition for your clothes.