A popular vacation hack claims that placing paper over your sink drain and covering it with an upside-down glass can stop sewer smells and insects from entering your home while you are away.
The idea comes from a real plumbing feature called a P-trap, the curved pipe under sinks and drains that holds water to block sewer gases and pests from traveling back into your house.
The problem happens when that trapped water slowly evaporates during long periods without use, leaving an open path for unpleasant odors and insects.
For most normal vacations, this usually is not a major concern because the water inside a P-trap can remain for weeks, but hot climates, dry air, and unused drains can make evaporation happen faster.
