Robert Dallek has a nice article today in Salon about the puzzling post-presidential reputation of John F. Kennedy, who shows no sign of slipping in the public's esteem, even as fewer and fewer are around who actually remember him or voted for him.
Dallek also notes that Ronald Reagan does well in post-presidential polling, and attributes it to mainly to style, I think; he calls Kennedy and Reagan "master psychologists of the middle classes."
Perhaps. As usual, I lean towards institutional explanations, and to our old friend the one-sided information flow. As I've said before, four postwar presidents have had serious, sustained efforts to enhance their reputations. Two, Jimmy Carter and Richard Nixon, were essentially single-person efforts. The other two, Kennedy and Reagan, benefited from publicity campaigns on their behalf. That model seems to be the successful one, especially long-term. The result of that kind of campaign is one-sided information flow, because there's not much of any reason for anyone to waste their time agitating against an ex-president.
(Similarly it became logical for lots of reasons for New Dealers, including New Deal historians, to praise Woodrow Wilson, which in my view is the reason for Wilson's overrated reputation).
As far as I can tell, which presidents get this treatment is almost random. Kennedy happened to have a large, wealthy family and many talented staff and supporters interested in that sort of thing; that does sort well with what I think was a very personal presidency, but there are other personal presidencies that didn't generate much after the White House. Reagan had a conservative movement eager for a symbolic leader. Carter and Nixon just happened to care about their reputations, apparently, a lot more than, say, Gerald Ford or either George Bush seemed to.
I'm not sure where to place Bill Clinton. He's certainly tried to be visible doing good works, like Carter, but (and perhaps this is just my personal sense of things) Clinton seems a whole lot less self-aggrandizing than does Carter. Sure, WJC is campaigning for himself and his party; no question but that he's a born politician, and he'll never really turn that off. But it just doesn't strike me as similar to Carter's never-ending quest for sainthood. Clinton is also, almost certainly, the most partisan ex-president in modern times. (Ever? Could be). And then you have the unique so far situation of an ex-president whose wife has been a national-level politician; I don't know if that should be interpreted as part of Bill Clinton's publicity campaign, or as something that distracts from any efforts he might want to make to enhance his reputation.