Making your band create a crappy version of a great song doesn't just cause people to get annoyed because they enjoyed that original song, it also causes people to hate your band because they now have an instant reference point; Limp Bizkit once did a number of covers of songs by The Who, causing me to hate them before even listening to their own unique output. Why? because I'd heard what The Who had done with these songs, making them into operatic yet conservative pieces of enjoyable rock, clearly songs made in the 60s/70s yet also not at all trapped into the cultural landscape like so much music from that time is. I could instantly compare that sound - which represented all that The Who was (and apparently still is, despite wanting to "die before I get old") - with the sound of the Limb Bizkit version, which felt like another piece of generic rock music. Their cover of "behind Blue Eyes", my favorite Who song, was their biggest offense, mainly because they took off the uplifting second half of the song and replaced it with some weird technology-heavy weirdness (or so I remember, I'm listening to Zeppelin right now and sure as hell aren't turning them off to listen to Bizkit).
So where am I going with this? and what the hell does it have to do with the title. Well I could scour the internet for every cover version of all your favorite songs, but I want to draw your attention to just one of your favorites: Nirvana's "Smells Like Teen Spirit", and the Miley Cyrus version I first heard only last week. For your own viewing pleasure (instant disapproval?) I've embedded the video below:
Now before I talk about that I want to say that i do know what the generally accepted terms of a good and bad cover song is. The obvious choice for what a bad cover song is obviously one that ruins the original music simply through a strange instrumental choice, bad music skill, or bad singing, but I'd also argue that a bad cover would also be a song which boringly tries to replicate the original exactly how it is. A good cover on the other would be a musical act using the original song as the basis to create their own piece of great music. I'm not saying it has to deride that far from the original source, but a carbon-copy of the original song isn't a cover, it's band practice.