Self-deprecating humor (and all humor really) works best when it humanizes the comedian. This is especially helpful for celebrity candidates like Reagan who have a tougher time being seen as "real people" just because of their status and careers.
It's important, though, that the source of the humor isn't something that is a real driver of actual negative sentiment towards you, and joking about something about yourself/something you did that people find genuinely off-putting is a very bad move and can in fact reinforce negative narratives.
Conan is one of the greats in self-deprecating humor IMO.
(Referring to his now-former talk show)
"...thousands and thousands of hours watched by hundreds and hundreds of people."