Why doesn't ancestral grave sound like a good word?

The ancestral graves emit blue smoke, which is a geomantic saying. Blue smoke is not only a slightly blue gas, but also an auspicious gas, which is an auspicious sign and can be used as an official in the past.

But saying this now can also be understood as swearing. Others say that they are incompetent, relying on the shadow of their ancestors and being lucky.