It's Google's fault, since they let sites backdate themselves and take the date as gospel. Luckily it's not all that widespread/deliberate, since backdating you

It's Google's fault, since they let sites backdate themselves and take the date as gospel. Luckily it's not all that widespread/deliberate, since backdating your site is basically asking Google to downrank you. I'm sure Google must keep track of things like date of first index, but if they do they don't expose it.