If you don’t prepare your client in advance about what they should expect from a tile or stone installation, then when the job is done, they may react as if it is a failure. The best way to avoid these types of false expectations is to educate your clients up front. Let them know the grout color will vary to some degree and won’t match the color chart exactly. Let me know that there will be some tile lippage, but within the allowable standards, because that’s an inherent characteristic of tile installations; tile isn’t perfect either!
Give your customers choices to avoid false expectations. Let them know that they can have crack isolation protection, or floor warming, or waterproofing, or stain-proof grout for an additional cost. Tell them the pros and cons of doing so. If the customer is informed of the trade-offs and makes the decision to go forward, then they won’t have false expectations and will be satisfied with the final installation.