Depends how you use it. When someone uses a font like Comic Sans sparingly, you can infer there's something special about this text. That maybe, this particular snippet is either a joke, or an informal formulation, or an XKCD quote. It can indeed be the author signalling that this snippet should not be taken very seriously.

But if the font is used by default, you cannot reasonably infer credibility from it. If the whole thing feels less credible or less serious anyway, then it's a status issue.