Nooo
Depends on the folklore:
Eastern Europe mythos favored iron stakes with the idea that pinning the heart will stop something from rising again. (Paint is fine)
This later mixed with ideas of sacred woods as symbol of purification (Oak, Ash, Hawthorne) to end a possession of the dead. (Paint not fine)
Most often I describe them as crackling black bolts or a desaturated grey-green color to play up the shady nature of its origin, but I agree with the “varies by patron” way of thinking
