Here's a treasure: a website dedicated to identifying what Samuel Johnson did not say--insights, witticisms, sententiae, apothegms, attributed to the great man but not his at all.
I came by it honestly. In a different place, I was recalling that "a favorite boss of mine (sic) liked to say--'Samuel Johnson says the way to judge a man is by how he treats a person who can't do him any good.'"
I had the wit to add: "I'm not sure Johnson said it, though he might well have thought it." Bully for me on that because the not-say web page (which I discovered only later) is quite emphatic that, notwithstanding a diligent inquiry, it cannot be found in the works of the great man. Ann Landers, maybe. Apparently Johnson did say "a decent provision for the poor is the true test of civilization," which is perhaps close enough in spirit but the main line remains untraced.
Just in general, it is interesting how quite a few items of non-Johnsonia, while clearly not his, do seem to fall somewhere within range of their target. Other great attributees--Yogi Berra, Mark Twain, Will Rogers--seem to me less lucky: they have to bear the brunt of any random quote a person might want to lay on them. By the way, is there a "what Yogi Berra did not say" page?
Attribution: what kicked this all off was Keith Humphreys' fascinating post here.