Is there any way (by script or not) to make a browser refuse cookies?
I have my personal browsers set to refuse all cookies unless from specific websites - every now and then I find a website whose page load performance goes down noticeably - once I saw pages that would server-side-crash when requested with cookies disabled (a Microsoft ASP.NET “undocumented feature” that makes certain websites untrackable by the GoogleBot but keeps them nice and clean to the Bing bot).
Not with the public instance. In a private instance you might be able to update the browser template for Chrome or Firefox to include the cookie blocking settings and then the clean browser profile will include the settings you configured.