Yep - this is something that I'm thinking about actively. How do you start the conversation in an interview (as either interviewer or interviewee) that gives you insight into how people treat problems? Is their instinct more individual or systemic? Do they naturally look for improvement, or point fingers?
I've had some success, but they're always very deep interviews, which can either be drastically good or quite startling to the other party depending on what direction it goes. So your note to do it 'tactfuflly' is very prudent.
I have often found that two things work well for this:
* have your antennae out for anything that seems weird (weak signals, indeed) in your conversations about the work
* check references (as an interviewee). That's a fancy way of saying, look to see if anyone you know knows someone who works there, who can give you the straight scoop.
So instead of asking "are you Kaizen?" you would ask about practices performed that imply Kaizen, including the spirit of the law and not the letter.