My top worst cover is Smells like teen spirit by Miley Cyrus, Its the biggest insult to Cobain (RIP) I have ever seen! Although as people have already stated, Jacks Obsession by Sparklehorse is Just terrible. This is to say though, that as long as the band that covers it does not truly get what the first band was trying to convey with that song, the cover will always suck because nothing new is added but a lot is stripped away.