Cory Doctorow makes an excellent case against copyright law in its current form.  In this brilliant article for The Guardian, When Love is Harder to Show Than Hate, he deftly identifies the irony of copyright law- it encourages people to tear down the work of others, rather to celebrate it.  In other words, using the work of others for critique or satire is more likely to be a 'safe' use of copyrighted material than any kind of celebration of the same material.  Granted that not all critique is bad, and not all satire is done without love - but his point is well taken.  

The upshot of this is that you're on much more solid ground if you want to quote or otherwise reference a work for the purposes of rubbishing it than if you are doing so to celebrate it. This is one of the most perverse elements of copyright law: the reality that loving something doesn't confer any right to make it a part of your creative life.