When is Google AdSense NOT appropriate for a site?

As in, is there any drawback to adding a revenue stream like Google AdSense whether you are Amazon.com or Subway Sandwiches? Why or why not?

Thanks for the response - I should have specifically mentioned that those types of sites are given exceptions.

Google lists types of sites that are not acceptable to Adsense

https://www.google.com/adsense/support/b...

However some sites do well with Adsense, while some sites are notorious for low performing Adsense, and still others raises the question whether it is a good idea to use Adsense

Take for example a site selling web design services. If this site shows Adsense, Adsense will definitely show ads from competing web design services. This raises the question of whether the site can earn more from its web design services or from showing Adsense ads. Because a click on the ads is a potential customer loss for the web design business.

Or an ecommerce site, where Adsense will display ads from competing online stores.

What some do is to display Adsense on their information pages or additional resources/articles -- pages that don't sell. They do not put Adsense on their product or sales pages.

When your site content involved promoting racism, porn, hacking, illegal drugs, gambling, guns, alcohol, cigarretes, selling fake stuff, piracy, etc.

You should check google adsense policy for a more complete list.