No matter how horrible it is in quality, English, etc. I like to keep it posted, or at least hidden somewhere. So that I can go back and see how much I've changed over the years. It's sentimental, of course, but it's also an indicator of growth.
I like it when my friends don't delete their things either. Like their stories, drawings, journals. Doesn't even have to be on dA (I'm talking about real life, too). Because things change and we forget.
If I have the space and the reason, I like to keep my old work.