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!