How much do lyrics mean when you're listening to a song?

I'm currently listening to Heaven or Las Vegas by Cocteau Twins, where you have a very good case discussing the importance of the lyrics. (To me) it's absolutely impossible to understand what Liz Fraser is singing, but this doesn't change the fact that I think it's a fantastic song, which basically means that I don't think that the lyrics are all that important.

The lyrics to the song can be found here - check out for yourself if you agree that this is what she's really singing!