Yeah, best to check out any drywall where pipes go through that might sweat, and even painted window sills of old windows that sweat in winter time for black mold. My neighbour owns a renovation and construction company, and he has so many stories to tell, like bathroom ceilings that were literally black without any of the paint showing through. lol
Luckily that shit doesn't compete well with other molds or bacteria, so you don't find them infecting planting medium.