Green’s Dictionary of Slang

1. unpleasant, disgusting.

1991

C.E. Hill (informant, Johannesburg) in DSAE 171/2: Cotch (adj.). Unpleasant. It was a cotch job I had to do.

2. pertaining to vomit.

1983		Grocott’s Mail (S. Afr.) 18 Feb. 13: Kotch Creek, Scenic brook with algae of undisclosed origin [DSAE].
1989		T. Botha in Style June 112: The Radnor Hotel in Hopetown looks inviting, much better than the kotch-green one back in Strydenburg [DSAE].