A "Google Dork" is just a fancy name for an advanced search query. By using operators like intitle: (which looks for words in a page's title) or filetype: , you can find specific information that a normal search would miss.
If you take one thing away from this article, let it be this: Always assume it is public. Use environment variables, use secret managers, and regularly search for intitle:"index of" on your own domains. Because if you don’t find your open secrets, someone else will. intitle index of secrets