A pushy salesperson will convince her to buy something she does not really want. Everyone will look at her furniture purchase for years to come, and know she made a mistake. And, trust me, you will be proud whenever any guest comes into your home. This phrase works because it is simple, and any salesperson can understand and execute it. It is so important that it is done well because there is no way to guarantee it.
Service is really like that.
People know they are at your mercy when it comes to service. Selling service is selling the invisible, and you are in the service business. Trust is critical. But, once you give customers the gift of confidence, you have added value to your products that nothing else can come close to. Next day delivery, one year same as cash, price guarantees and all the other table stakes are good for the close.