befoul

These heights are a desirable retreat, for less picturesque reasons—as an escape from a compound of vile smells perpetually arising from a great harbour full of stagnant water, and befouled by the refuse of innumerable ships with all sorts of cargoes: which, in hot weather, is dreadful in the last degree.

For its an ill Bird will befoule her own Nest […]

For three days Pete bore himself according to his wont, thinking to silence the evil tongues of the little world about him, and keep sweet and alive the dear name which they were waiting to befoul and destroy.