Just speaking for myself....
If I'm working in a house, I do not want flash photography at all. It's very annoying and can be incredibly blinding. I'm against taking photos or video inside a house anyway. People should concentrate on the atmosphere, scares, and story and not trying to focus on taking away mementos.
If I'm working in a scarezone, I'm pretty flexible and can usually transition from photo taking to scaring pretty easily. I'll usually accommodate with poses if you ask nicely. However, if I ignore you, don't take it personally because I'm probably either busy scaring or under orders not to do photo ops. Flash photography outdoors doesn't bother me, but don't suddenly light up right into my eyes when I'm not expecting it.