My interpretation:
(I'll use the lyrics)
Load up on guns, bring your friends
It's fun to lose and to pretend:
This is Kurt Cobain's horrid and morbid view on society. Consider this the thesis statement for the entire piece. We are a violent society and we are fake but it's seen as fun.

She's overboard and self-assured
Oh, no, I know a dirty word:
The dirty word here is Self-assured. This is because everyone in society is fake and or "pretends." Thus "self-assured" is a dirty word.

Hello, Hello, Hello, How Low (x3)
Hello, Hello, Hello

I think this bridge serves 2 purposes.
1. it begins the satire on his fans and society as a whole. the "how low" is done in a low octave, thus Kurt is questioning how low he has to make his voice for society and telling us about it.
2. The hello part is Kurt saying his hello's to society and begging us to pay attention at the same time.

With the lights out, it's less dangerous:
metaphor; the "lights" is a metaphor for the mind. He's stating that without thought the world is a less dangerous place which in turn goes back to the pretending and fitting in with society.

Here we are now, entertain us
I feel stupid and contagious
Here we are now, entertain us:
Satire. He's figuratively pointing the finger at us, his fans and making fun of us.
we are stupid and we are contagious but we don't care because we are entertained.

A mulatto
An albino
A mosquito
My libido
Yeah

society as a whole is described right here.
A mulatto: who cares because it's still a human.
An albino: who cares because it's still a human.
a mosquito: those suck blood.
My Labido: those want sex.
Humans are blood sucking mosquito's who only do things based on their own selfish labido's...
yeah!

Hey... Yay

again; satire. Kurt is pointing all of this stuff out to us but he's like yay! because we as humans are horrible but it's ok because we all pretend and YAY!

second verse:
I'm worse at what I do best:
He's bad at this because no one gets it. I mean here we are 20 years later and I have to post this. No one will read it and it will be seen as wrong because Kurt was worse at what he did best and that's viewing society differently.

And for this gift I feel blessed:
self explained and one of the only parts in which Kurt points the finger at himself. He knows he also is a part of society but he gets to view it under his own certain light and sell it thus he feels blessed.

Our little group (tribe) has always been
And always will until the end:
Again Kurt points the finger at himself yet he does it in the terms of his own small group. Kurt is admitting that he to belongs to a society. Kurt is admitting that he to pretends. His little group is a metaphor for society and how even he has to conform.

And I forget just why I taste:
Again, satire. Kurt is questioning why we pretend and why we as a society accept our fake personas in order to fit in and in order to survive.

Oh, yeah, I guess it makes me smile:
His answer. We all have to fit in to society in order to achieve happiness.

I found it hard, it's hard to find
Oh well, whatever, nevermind:
Here Kurt is questioning what this all means. With all of the ideas he has put forth about society and willingness to conform Kurt is questioning why life and society as a whole exist. Kurt doesn't know the answer and so "nevermind"

A denial is said near the end of this song and it is repeated multiple times. I believe it is repeated to force the listener to hear the denial but what is this denial?
Is it a denial of ourselves?
is it a denial to view society for what it really is?
Can I go back and make this about a woman whom is a lesbian? you bet your ass I can!

That's the beauty of artist such as Kurt; this song can mean multiple things to multiple persons. I am merely posting my explanation.

So why is it called smells like teen spirit you ask? I think my explanation is the correct one and the title "Smells like teen spirit" was simply made to lure listeners away from the deeper more complex meaning.

A small jab at an ex girlfriend never hurts.