Plants that grow in low-light conditions become pale and leggy. If your pothos plant leaves are variegated, they will probably first lose their variegation and revert to green to compensate.
Temperature stress can lead to the development of white leaves. In more severe cases, when the temperatures are below 50 or above 90 degrees F, the leaves will develop discoloration and wilt.
When you overwater a pothos the stems and leaves become pale yellow or white, soft, and mushy. The soil has an unpleasant, rotting smell. When you dig roots, they are watery and dark, later decaying, and almost non-existent.