It's not disingenuous or superficial if you exercise the advice earnestly. For example, don't just "act interested", but "be interested" in what the other person has to say.

I assure you that doing so is both extremely difficult (because we're selfishly interested in ourselves most of the time) and kind (because the other person rarely receives such selfless attention.)

It's only cringe inducing if someone is using these tactics without actually being interested in others. Carnegie definitely does not advocate for being such a person.