the internet cache

Has anyone came across any cases of the internet cache where someone has argued that they have not seen something on a site, but the cache suggests they have - or conversely, internet history shows a visit to an evidential site, but they argue that they only just clicked on it and straight off? If so, did you manage to prove anything to support / refute any arguments?

Or in most cases, is it just a case of 'if its in the cache' then its been seen online by the user?