All three artist in the OP definitely..
Manaj - Can't rap to save her life. Rhyming a word with itself doesn't count as rap...and the hell is she doing with her voice when she "raps"?
K money symbol ha - Talking isn't singing.
Lady Gaga - 2 words: Attention *****. I understand some artists doing quirky things sometimes, but she is constantly doing it and the sole purpose is basically "hey! Look at me! I'm different! Look at me!!"
Swift - Maybe the problem is you Swift? Just because a boy isn't madly in love with you after 2 months of dating doesn't mean he is a bad guy...
Bieber - I'll admit..he can actually sing. Just not as well as his voice sounds on his album songs. Oh...and don't claim you are great at drumming when the best solo performance you can do is one I (who has never played drums) could learn in 30 minutes
LMFAO - "Hey...maybe we should have what we say actually mean something? And maybe we should actually sing instead of mumble crap?" "Yeah...but that's dumb!
Most mainstream rapists - It's ok...rapping that slow and pathetically is hard for me too
Most -core bands - Do you even riff? (*hint meme reference here hint*)