>Philosophy of Science, I think, is almost a completely bogus field.
A coherent philosophy of science is required for science to be based on valid premises. I don't know what you mean by this, unless you're referring to something recent which I don't know about. The past philosophy of science has been extremely instrumental to creating the scientific method; Karl Popper is science household name.
>On the other hand, it's very political, and a lot of it is mental masturbation.
There's nothing wrong with political philosophy, and arguably political philosophy is some of the most important from certain perspectives (pragmatism?). There's also nothing wrong with mental masturbation; by the same measure art, abstract mathematics, theoretical computer science, theoretical physics, poetry and a vast array of human literature is also mental masturbation, yet few would deny its value.
I have a hard time dismissing Hegel and Marx because their work involved political philosophy.