it means nothing.
I've seen SPs in Montreal with "open minded" in their ads. they were no different than regular GFE. many extras not on the menu
I kind of agree with the above as I have seen girls advertised as GFE but service provided was super PSE (Really, really "OPEN" minded).
Then again some agencies may use the term but (Maybe) the girl has no idea that she is advertised as "Open minded" hence the basic service.
Like many of us over here have experienced very very **open minded** girls without advertised as such,
so at the end, depends on the advertiser, if no GFE , PSE or itemized services are advertised,
then maybe it does not mean much.
** to name a few. Anna, Hanna, Sonia, Chloe, Shelly, Katia, Victoria Mini and etc, few others can't recall
the names at this moment...