While Virgil Ross wasn't able to be as loose as the other great animators, he was always able to deliver with facial expressions. This scene from A BIRD IN A GULTY CAGE (1952) is a perfect example.
Sylvester's reaction to each hat is different and distinct: he sticks out his tongue and shifts between poses in deliberately limited movement; his face droops from a broad smile to a depressed frown; and, of course, he winds up looking devious yet stupid as he spots Tweety perched on top of a hat.
The whole scene is perfectly in character for Sylvester even though he doesn't talk and is doing something seemingly uncharacteristic for him. Ross gets to the essence of the character -- what's likable and what's pathetic about him -- with small but perfectly executed movements.