He had seen Bud drinking.

Bud knew perfectly well how much Joe had seen him drinking, and he knew perfectly well that Joe was surprised to the point of amazement--and, Bud suspected, secretly gratified as well.

Wherefore Bud had deliberately done what he could do to stimulate and emphasize both the surprise and the gratification.

Why is it that most human beings feel a sneaking satisfaction in the downfall of another?
Especially another who is, or has been at sometime, a rival in love or in business?
Bud had no delusions concerning Joe De Barr.

If Joe should happen to meet Marie, he would manage somehow to let her know that Bud was going to the dogs--on the toboggan--down and out--whatever it suited Joe to declare him.