If you can read “on” or “off” it’s time to clean the light switch plate covers. Think of how many times everyone in your family touches this item every day. Germs, fingerprints, smudges are a given.
I’m pretty sure it’s a big factor in passing around the same cold and flu germs from one of you to the other.
Heat up your steam cleaner, cover a small brush with a cloth and gently steam the plate and the switch from a sideways angle until it’s clean and sanitized. As long as you don’t shoot steam directly into the openings, you won’t risk shorting out any electricity.