Headlights cloudy?
The reason this happens is the lens' have a UV absorbing coating on them that eventually gets consumed by UV, abrasion(washing) and chemicals. The UV can then attack (fog/haze/yellow) the raw underlying plastic.
While you can polish them bacl to glossy, the missing coating ensures they will fail in a short while.
Taking the step to clear coat them with an appropriate UV absorbing clear will give the many years of clear service life.
The more you know!