@grievoustim – matter of taste, obviously, but I’d contend that Ms Cole, whilst possibly the weakest singer in the world, has picked a couple of decent producers/writers. Certainly Boy Like You and Stand Up are decent bits or work, though obviously a different singer – almost any other singer – would improve things.
Katy Perry’s had a couple of hits, but the recent album is just a shocker. California Gurls is a genuinely poor song, and despite her being personable and clearly game for almost anything, the songs are awful.
Earplugs a must, to answer another question.