Green’s Dictionary of Slang

1. covered in excrement.

1904		Sydney Sportsman (Surry Hills, NSW) 27 Apr. 3/7: Why are modern british soldiers like dirty little boys of three? [...] Because they wear kharki pants.
1937–84		Partridge DSUE (1984) 172/1: late C.19–20.

2. in fig. use, disgusting, second-rate.

1938		H.M. Anderson Strip Tease 41: [of a ‘dirty joke’] Jake can tell dirty jokes without offense [...] he’s gotten away with ‘cacky’ scenes by making them cute instead of dirty.
1972		B. Rodgers Queens’ Vernacular 40: cacky (fr kaka = shit, reinforced by tacky) repulsive, ugly.
1998		Guardian Sport 25 Sept. 16: A lemonade top on this cacky red wine what’s been ordered in.