A simple water test can help determine if your floors need refinishing. Place a few drops of water on the floor surface – if it soaks in immediately, the finish is worn and needs refinishing. If the water beads up, your floors may just need cleaning and polishing.
Visible scratches that catch your fingernail, areas where the wood shows through the finish, or widespread discoloration are signs that sanding is necessary. Surface scratches and dullness might be addressed with screening and recoating, which is less intensive than full sanding.
Professional evaluation is the best way to determine the right approach for your specific floors. An experienced contractor can assess the finish condition, wood type, and previous refinishing history to recommend whether your floors need full sanding, light screening, or just professional cleaning and maintenance.