As a general statement, mold is not good, when caught early, it can be cleaned and the bit can be placed back in use.
The real questions is: What is causing the mold? Some parts of North America are naturally more prone to mold development that other parts. So, those areas, one must be more proactive in finding and removing it.
Other areas experience season issues with mold. Or, as a result of a water leak, mold develops in those areas.
Understand the source and repair it, if it's a leak issue. Or, clean regularly if your in an area that is prone to mold developing.