Isn't a guilty pleasure something most people would regard as irredeemably naff? Like John Denver or James Last. There's nothing wrong with liking some well-crafted pop for example - and Tatu were nothing if not well crafted...
My guilty pleasure is a Japanese easy-listening guitar duo called Gontiti, who play simple versions of standards - it's utterly undemanding and in no way cool at all. Oh, and Glenn Campbell. Even my wife laughs when I play him. But I think he has a classy voice and I like the very ordinary romance of his songs: Wichita Lineman is lovely.
PS: I am saying nothing about Rush because I have said everything I have to say about this abomination before!