And, of course, the answer to her question is that they can't. Sure they can quote the Bible. They can tell you how the Church interprets the passage, how they themselves interpret the passage. But good advice is a sharing of experience and as long as clerical celibacy is the rule Catholic clerics will not be able to give good advice on most of the problems people face.
Following your logic, a therapist or psychiatrist cannot properly diagnose and treat ailments he/she has not suffered from.
I've seen this argument many times, and it does not hold water. It would mean that an unmarried priest couldn't give advice about marriage. And a married priest without kids couldn't give advice on child rearing. Of course, a married priest with only boys could not give advice on raising girls. Yet we don't require licensed marriage counselors to be married.
You see, you can twist that logic into many empty justifications.
Priests are privy to people's innermost confessions. They receive information that is often not transmitted even between spouses. They can provide the kind of insight which can only come from one who is an outsider to the relationship. Whether that advice comes from one who is married or not is irrelevant. Who would you rather receive marital advice from: Pope John Paul II, who is celibate, or Bill Clinton, who as we all know is married?
Furthermore, do you ever advise anyone? Using your standard you can never really do so, as you will never experience what it is to be subjectively in their shoes.