It is not unheard of to refund an entire inspection fee or more. Sometimes a simple letter offering such a rebate when a problem arises goes a long way toward capturing future business. You should always state that you have met the standards outlined in your contract if you believe you have. If this is new to you, consult first with someone who has expertise in this area. Someone taught me many years ago that in business it never hurts to be nice.
Service is the most important part of our business.
You might consider how you can go the distance for your clients. Prepare every report as if you will have to defend your words in court and justify your findings using a good report designed to reduce liability. Meet the needs of your clients by giving them a realistic expectation about what an inspection is and isn't designed to do. Produce a competent report and present it well. This is how you gain the respect of clients and agents and ensure success in this industry.