This happened during a tour with the owner of an office building.

Client:  The landscaper is doing a terrible job!  Look how dusty the leaves are on these plants!

Me:  You mean these leaves?  On these outside plants?  These plants located outside, planted in the dirt, outside the building in the sun and rain and wind?  These outside plants located outside?

Client:  Yes!  The landscaper should be wiping down all of the leaves to keep them clean!