As Philip Kennicott argues forcefully that money from the arch-conservative, climate change-denying Koch brothers is by now irredeemably tainted, Lyn Gardner looks at the ongoing arguments over arts sponsorship by BP: “Whenever the cultural sector is benefiting from cash injections, the question must be asked: although it may bring benefits to our theatre and audience, is there a price for this sponsorship that is being paid by someone else, somewhere else?”