Grime

Mark bought a pressure washer.

He hooked the contraption up and told his wife (Judy, currently sunbathing) to shield her eyes.

She was blasted with the powerful jet.

Judy staggered to her feet, drenched.

Mark consulted the marketing material.

Informed Judy how many years of grime this thing was capable of removing.

Judging by Judy's expression she wasn't even remotely interested.