Sorry if this has been discussed before, but I was wondering why Google even allows Adsense on Adwords landing pages? Presumably, if you're advertising with Adwords, you're selling a product. Having Adsense on the landing page is what makes arbitrage possible for the MFA spammers. Google should prevent this (and disallow redirects or cloaking) on the landing page.

The downside is possibly less money for Google overall due to fewer spammy MFA advertisers, though I'd imagine Google would probably make more since Adwords campaigns would be more relevant overall. Also, there's a possibility for a denial of service attack: your competitor buys a cheap campaign and points the landing page to your home page to prevent your Adsense ads from appearing. However, this would be easy to detect since Google can notify the affected Adsense account before taking action.