Devious Cover-Up can't target itself at all. You can't try to counter it with itself and shuffle cards in, and you can't use its effect to shuffle itself into your library.

A spell that can't be countered is a legal target for Devious Cover-Up. The spell won't be countered when Devious Cover-Up resolves, but you'll still shuffle cards into your library.

You may target zero cards in your graveyard and still shuffle your library.