I don’t have any reason to think these clips reveal something dark about Carson himself, but they do reveal a lot about the sort of race-oriented humor that was acceptable on television even in the late 1970s. The second clip is from 1976 and features a jive-talking Carson in blackface – or, to be more accurate, half-blackface. Johnny Carson! In blackface! In 1976!
Further background: the caustic (and wicked) Bamboozled.
Update: Was able to download the clip – and it is indeed clear that Carson is mocking Rickles’ racist style of comedy. Much intense discussion on Metafilter… But is blackface acceptable in any context? And I mean that sincerely – as much as I enjoyed Tracy Ullman singing ‘Sit Down Your Rockin’ the Boat’ on her show – she was in full blackface make-up and she is a master of transformation. But is it always in bad taste – is this a distinctly American pre-occupation? And does anybody but blacks and whites really care?