Green’s Dictionary of Slang

1. miserable, miserable-looking.

1872		E. Crapsey Nether Side of NY 92: The words being spoken at two o’clock in the morning in a basement coffee saloon which had the one merit of cheapness, and the speakers being men of generally mildewed appearance.
1890		Bulletin (Sydney) 5 July 18/2: [S]eeing that the new genius can already reel off the old mildewed idioms and worn-out phrases of the training-stable, there was no occasion to hint at his want of fluency.
1946		H.A. Smith Rhubarb 23: I’m going to throw you so that your mildewed carcass wraps itself around that tree.
1959		I. & P. Opie Lore and Lang. of Schoolchildren (1977) 181: Mardy, mildewed, mingy.

2. pitted with smallpox.

1923

J. Manchon Le Slang.