I agree in a general sense, saying a certain band is of a certain mileau would not work with, say, someone not knowledgable of metal. My main issue to start with was when you called Babylon Whores Goth-metal, labelling is not something I'm prone to rely on, but the eventual point I'm working to is that labelling can be useful when used correctly and with "common sense". Common sense to me, in this particular case, is implied not on the receiver's end but on the part of the person imparting the "knowledge". What I'm getting at there is that as long as you apply the label with a good degree of understanding and not throwing it around without a clue of what it actually means.
From where I'm sat being negligant in applying a label can end in the person on the receiving end get the wrong idea. For instance, you called Babylon Whores Goth metal, now from my perspective I've got four CDs by them and they only in one song could be described as such, to me it's being slightly (I use this word lightly being as I cannot think of a suitable replacement) irresponsible to say that it is in that general style gives drastically the wrong impression of the band's music. To me that shows little common sense...
(in fact I know this, because I might call a piece by Wagner a classical piece, all the while someone who is a semi-expert in this music would be shaking their head at my complete ignorance... my lack of "common sense").
Common sense is a hard thing to define but in context of your use of the word it seems to me that common sense is not what you are talking about... you're talking about knowledge. Common sense is not something you're born with, I agree, it's something you learn over time... like it's common sense you don't play with knives, see? It's something that is born out of understanding... I understand a knife is sharp, so therefore it's only sensible not to play around with one. Which is where this Classical music thing falls flat on it's face. If you have little knowledge of classical music how can you have any common sense as to the application of labelling a subgenre within it's confines? You can't.
What I'm trying to get across is that if you know something of a style and you think that a label fits then why should that be a problem? There is no standard definition of Death Metal, but in all the time I've known about Cannibal Corpse I've always heard them referred to as such it's a highly shared viewpoint that they typify the style of death metal, for good or worse. I don't think you should throw sub-genre labels at someone who is new to it, I don't think you should label things without some experience of them, and in all I agree, it's pretty fucking crummy that we live in a pigeonhole society and everything has to have a neat little tag... But I just don't think the general stigma that labelling is always going to be wrong applies as long as you just don't throw it in without some thought. It does seem to me that when you say this:
It doesn't work very well to label bands. It isn't efficient. It's only convienient, and it doesn't get the job done
that you're taking a very hardline view of what I'm saying, like I'm suggesting we should all do it and it's perfect, I'm not saying that, I'm saying it has a time and place and it does require a bit of thought and judgment too.
Incidentally I don't think descriptions are all that infallible either. If you were to describe Cannibal Corpse's music how would you go about it? I'd say it's very aggressive music, heavy, technical guitar riffs, sporadic blastbeats and growled vocals, fair enough description? Well I've just described hundreds, possibly thousands of other bands, and that crosses genre labels, that could be anything from Grindcore to Black Metal. There's nothing efficient about that now is there?
I've only heard it over the phone a few times though, so I guess I can't really say until I get it and hear it first hand.
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Hope SOMEONE out there understands my point. 
