I agree with njbmd - I can't think of any questions that would be off-limits (unless they were of course, personal in nature - ie, my weight, sexual habits, etc. 😉 ).
If a program is offended and think you too nosy, then perhaps they are either
a: hiding something (it has always been my feeling that those who get angry when you question them are hiding something...NB: hope ex-boyfriend sees this)
or b: not the program for you.