Do fog-free shower mirrors really stay clear without fogging?

Most so-called fogless mirrors work one of two ways: a passive design that you pre-warm or wipe, or a heated/anti-fog coating. Across the verified-purchase reviews we read, simpler passive mirrors generally need a quick rinse with warm water (and many include a squeegee) to stay clear, while heated models stay fog-free longer but require charging or power. No mirror in this pool was independently lab-verified to be permanently fog-proof.