In the earlier days of the Internet domain names (e.g., .com, .org) were generally more meaningful than they are today. Now there is often little distinction between a website with a .com or a .org domain. And while .edu indicates that a webpage is affiliated with an institution of higher education in some capacity, you should look more carefully as what that affiliation is (for example, a personal website of anyone who works or studies at that institution vs. the official website of a research institute affiliated with that institution).
In other words, examining a web site domain is one method in a multi-step process in evaluating a web site, but it is not always a gold standard methodology in determining the credibility of a web site. Just because a web site has an educational domain (.edu) it does not make it more credible than a .com or a .gov. Using lateral reading techniques introduced in our workshop can help you determine if a website is credible. In short, there is no shortcut to spot a bad website from a domain alone.