When I've met people like David Frum, I made a point not to buy his book, and wait until the people who did had theirs signed, and then asked him if he could relate to David Brock, who was a right-wing propagandist whore (I didn't use that language) and came to realize how wrong he was for it, to point out to Frum he could benefit from doing the same.
Frum did not seem to get the point.
When I talked to Kevin Phillips, who I think highly of for his work for years now but who played a terrible role in helping to end the liberal era from FDR to LBJ by helping Nixon defeat Humphrey, I asked him if, as he has changed his understanding of the right-wing agenda, he feels guilty for his role. Unfortunately, he does not, somehow reconciling his support for Nixon as ok, while abhorring the later result.
Oh, I did go to the Richard Nixon library and make a point to use the urinal as a symbolic act.