Well I throw out clothes that don't fit me, otherwise I keep them, even if they are ugly lol. But I'm a fashionable person so I MUST have elegant/sexy clothes, otherwise I feel like a teenager with hideous clothes.
I usually go through all my clothes every three years or so (when I run out of space for new things) and all the ones I haven't worn since the last time I looked through it, ones that no longer fit or are horribly unfashionable, I donate to charity.
I intentionally throw old clothes away (even if good quality) because there are many poor people here who need them and have no money. They deserve to dress well. So, I give them to poor people I know or to charity.