I just really get annoyed by movie ad claims that do this. Especially when it's done by horror, drama, or sci-fi movies, the typical culprits. Cliche hook indeed.
If there's recent evidence to be had, then there's 'The Fourth Kind', a movie based on 'psychiatric interviews' with people who 'have been abducted by aliens and lived to tell the tale'. For all anyone could know, the interviewees could be schizophrenic or something, and the only thing prying people from their money is that they just want a good scare, with nothing to care about regarding the 'real life story'.
Yeah, then it turns out that the validity gets investigated throughout the film. So much for being based on a true story if there's investigatory stuff within a movie that probably should've been confirmed pre-production or pre-release.
For the record, I'm reading this part off the IMDB site, so yeah
Gah, sometimes I realize why I'm not an avid moviegoer kind of person.