For example:

The website below, "The Organizing for America" website does not follow rules of social interaction. This is pointed out in the book and is a great example. You notice to view the rest of the website you must enter your email address and zip code. No one wants to give out their email to all of these websites to then get spam mail and doing so also makes some people weary.

You don't notice it until further investigating that there is a blue button below "Learn More" that says "Skip signup". Making this button hard to read is not only misleading but also makes your website seem untrustworthy. Imagine this as a physical social interaction; this is why people expect online interactions to follow social rules.