Which characteristic of creosote contributes to its handling difficulties?

Creosote is known for its dark color, which can contribute to handling difficulties. The dark hue makes it difficult to see where it has been applied, posing challenges during the application process. This can lead to uneven distribution, staining of unintended surfaces, and potential environmental concerns if not properly contained. Additionally, the dark color may mask the detection of leaks or spills, increasing the risk of contamination in the surrounding area.

The other characteristics mentioned do not inherently contribute to handling difficulties. For instance, being soluble in water could indicate easier clean-up, while leaving a colored residue can be managed with proper technique. Non-toxicity would imply a safer handling experience, which does not align with the challenges posed by creosote's dark color. Thus, the dark color is significant in terms of handling and application complexities.