to make (a region, water; a person's thoughts etc) dirty or impure

corrupt, violate

(to cause something) to lose colour, freshness or strength

lose color

to mark (something) with something oily or sticky; spread (something oily etc) on (something); a deliberate (often untrue) remark made against a person, product, business etc

rub on, spread over

dullness (on metal) because the brightness has gone; to lessen the quality of (a person's reputation)

dirty, corrupt