And the main reason was because the guy was genuinely funny, understood comedy, and was as happy to be the butt of a joke as to deliver a punchline.
I also saw a video of Foster Brooks roasting Jack Benny, and Benny couldn't help but laugh, laugh, and laugh some more.
I enjoyed Dean Martin and George Gobel.
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Another insight was from What's My Line, the game show where the celebrity panel was blindfolded and Benny signed in as Heifitz.
And while Jack Benny could deadpan a gag, usually he was on the receiving end of it, a few shows could give you insight into how much he enjoyed comedy, his show, and perhaps comedy in general.