I would think that any time a cat eats something unusual, it must be
the smell that entices them. Their sense of smell is so incredibly
better than ours that we can't ever truly appreciate how important
odors and smells are to them. Their experience of a smell must be
vastly different than our experience of it. And maple syrup does have
an unusual and pungent odor, especially compared to most things Buster
might ever eat. Maybe it's the sheer novelty of it that attracts him.

My Simon has never shown much interest in people food, although
occasionally I can get him to take very small morsels of meat or cheese
from my fingers. And he does enjoy jumping up on my chest after
breakfast to check out my shirt for toast crumbs. I think he likes the
butter. Sometimes he will pursue a crumb into my chest hair, which
tickles like crazy and makes me laugh out loud. When I was a kid I had
a parakeet who would happily spend half an hour at a time burrowing all
around under my shirt, occasionally popping his head out between a pair
of buttons and going "Meep?" before continuing his explorations. It
made the whole family laugh to watch him.