Of course it all depends... on how diligent the property is, who they hand out the master codes to. And in some instances, whether they change the default master (override) code!
YouTube video
here.
You may want to check this out at your next hotel - if the safe opens with the default code given, you may want to not put your passport, etc. in it.
OTOH, the key locked (such as "Safekeeper") ones are, er, safe, right?
Not exactly.