Let's say McDonald's pays us $500,000 to put an ad on [[Fast food]]. Is that compliant with [[WP:NPOV]]?
Yes.
What happens if McDonald's will pay us $500,000 to put an ad on [[Fast food]], but only if we nix the 'Nutritional value' section?
Then we say, "See [[WP:NPOV]]". Or perhaps "we" nix that section and someone else puts it back. This is a bit of a strange argument that has been made a few times. WP is WP. I don't think anyone is proposing changing its core principles simply because we start taking ads. And again, I don't see how placing ads on WP is compromising any of WP's principles in any way.
I'm not especially in favour of ads, but let's at least be sensible in discussing the possibility. :)
Steve