I don't rightly know Manic...honestly and I don't think anybody does. No, not really, its a term coined to describe music that exists outside of the realm of the music industry (or is widely ignored by the public) or ignores commonly held ideas about what music is, should be or how its played it. In other words music that exists outside of what people consider to be music(pop music, standards, ect)...for lack of a better explanation.
Well here, wikipedia probably does a better job explaining it then I can.
Outsider music - Wikipedia, the free encyclopedia
And yes some (or lots) of it is as bad as you can imagine.