What indicates that a fabric protector needs to be reapplied?

In the context of fabric protection, visible staining or soil accumulation that does not respond to cleaning is a clear indicator that the fabric protector's effectiveness has diminished. A fabric protector is designed to repel water and prevent soil from adhering to the fabric fibers. When stains or soils begin to accumulate and are resistant to regular cleaning, it suggests that the protective barrier is no longer functioning as intended. This means that the protective treatment has likely worn off, and reapplication is necessary to restore the fabric's resistance to stains and soil.

The other options, while they may indicate various issues with the fabric, do not specifically reflect the performance of the fabric protector. Discoloration over time can result from numerous factors, including exposure to sunlight or improper cleaning methods, but it does not directly relate to the need for reapplication of protection. Similarly, fading color due to sunlight exposure indicates degradation of the dye rather than the functionality of the protective layer, while uneven texture may signify wear but does not specifically highlight a loss of soil resistance.