I have seen that look of disgust so many times. The cat is thinking " Something smells like DOG". Poor Callie was off leash when he met our cats. He had a checkerboard patterned scratch in his nose for a long time. But he'll cross the room rather than anger a cat...they learn
My cat swipes at our new pup now and then, but I think it's a soft paw, not a serious claws out scratch, thank goodness. We did trim his nails recently just in case.