people drop the word so often it can become fairly meaningless, except as a way of saying that "i" find someone's work really moving or thrilling or top notch or whatever ...it's much like the word "awesome" or others of that type...
for instance,"the genius of ray charles" was an album title - subjective word, much hyped - and lots of people sniffed at that, claiming only one or another classical music bore - subjective , much hyped - deserved to be categorized as genius...
so no matter how you narrow any category, some will strongly disagree about something as subjectively arbitrary as that term, which means great, but even greater than some other great...
when i was young and lewis was working with dean martin, i thought he was a fantastic physical comic and at times he made me laugh so much i hurt...and never thought of him as making fun of disabled people but only playing the role of a man-child, which is what lots of great old comics did, seeming to react to the world the way a little kid would, or might wish to...lou costello was another favorite of my youth, one of those grown men who acted like a child and was funny - to kids and people who were not yet youth-dead! ... and lewis was a master....but i never saw a film of his, after he split from martin, that struck me as anything but boring and ego driven...
still, he was great...
maybe a genius to some, if not me...
so, big deal...we like(d) him...alot.
fs