In the case of Derrida, I'd recommend you take a look at Arkady Plotnitsky's article "But It Is Above All Not True": Derrida, Relativity, and the "Science Wars", in the journal "Postmodern Culture" (unfortunately now behind a paywall at MUSE).
The short version: Sokal (and those who follow in his footsteps) cherry-pick their quotes, and then refuse to read them in any kind of context whatsoever. To think that this has anything to do with forming an informed opinion of a philosopher (or other thinker) is ludicrous.
There is a plaintext version of the Plotnitsky article, and I think it addresses the Dawkins article so directly (though it was published one year earlier) that it bears a direct link here: http://www.iath.virginia.edu/pmc/text-only/issue.197/plotnit...
The short version: Sokal (and those who follow in his footsteps) cherry-pick their quotes, and then refuse to read them in any kind of context whatsoever. To think that this has anything to do with forming an informed opinion of a philosopher (or other thinker) is ludicrous.