The real problem is their offsite "Like" button and other offsite widgets. It is too easy to have these on a site, and users will think it is sanctioned/blesse

The real problem is their offsite "Like" button and other offsite widgets. It is too easy to have these on a site, and users will think it is sanctioned/blessed by Facebook. This effect is much more significant when the domain name ends in book.[tld]. This is a double-edged sword brought on by their success and operation.