Well, first off, that's a misnomer, really, as a guilty pleasure would indicate you were embarrassed by it, and I find the thought of being embarrassed by what you like to listen to a bit odd...
Warble aside, my housemate and I discussed this today.
Hers was all of Crossroads by Bon Jovi (she likes Bright Eyes, Glassjaw, NMH, Owls, all sorts...)
Mine would be Invisible Touch by Genesis, probably. And You Know My Name, by Chris Cornell, which I thought was brilliant at the time, and, now, well. Less Than Jake are still ultimate awesome.