This is answer 3B in "BizQuiz: Working with overeager horse owners."
Sometimes people just want to be heard. Even when you think their information is wrong, try to acknowledge your client's comments. Keep in mind that you don't have to agree.
If you think a client may be holding back, ask for his or her opinion. This lets you show clients you care about their efforts. Plus, you'll find out what they know so you can head off any barriers to compliance.