After my unfortunate purchase of a CD containing only cover songs, I've come to a realization:  Cover songs suck.  Even when you like the artist performing it, and even when you like the original song [*].  And there's a simple reason for it:  When performing a cover song, a band usually tries to mimic several aspects of the original song and the original band that performed the song.  This almost always produces bad results, simply because it's a difficult thing to do.  Each band has its own style and abilities, and those qualities often don't overlap.  In the unlikely case a cover song sounds as good as the original, a band has a good chance at becoming a cover band, which really isn't something to write home about.  Otherwise, a cover song is just a half-hearted attempt at reproducing something.  There are some exceptions to this rule, mostly when the band covering the song improves upon it in some way, or essentially recreates it.  But those exceptions are few and far between. 

[*] Or should I say, especially when you like the original song.  Cover songs I like are often covers of songs I don't like, so they're essentially new songs that happen to sound like old songs. #entertainment