Truecrypt didn't generate fake date, you (the user) did. E.g. put porn on "show to thugs" partition and "Death star plans" on "true" encrypted partition.
Poop porn? Also, besides keeping that, and starting VLC muted in the background from time to time to keep plausibility, you would use the porn tainted partition for your everyday stuff. Hacker news, etc.
"So, the decrypted hard drive says that you used the computer exactly once to put pornography on the computer and then never use it again ..."