Found one of those data generating databases ZIPskinny. It is, from a cursory glance, bogus. Here are some results:
The Top 100 ZIP Codes lists suggests that there are 69 places where the percentage of the population over the age of 15 which is currently married is 100%, that there are over 100 places with 100% high school graduates, 12 with 100% 4-year college graduates, 7 with post-grad degrees, and that there are places with median ages of 12 and 85. So, if someone suggests this site to you, look elsewhere.