Cattle, and especially hogs, are passionately fond of still-slop, and can scent it a great distance, so that no still can long remain unknown to them. It is a curious fact that most horses despise the stuff. A celebrated revenue officer told me that for several years he rode a horse which was in the habit of drinking a mouthful from every stream that he forded; but if there was the least taint of still-slop in the water, he would whisk his nose about and refuse to drink. The officer then had only to follow up the stream, and he would infallibly find a still.
(from Our Southern Highlanders, by Horace Kephart)