This: "...they usually try to clean the area where you can see..." says it all. Many contractors have a keen awareness of which shortcuts are easy to get away with. Most customers are clueless to this unless they are both knowlegeable and observant. Customers might check up on the contractors work progress once or twice or three times a day. During those brief inspection periods, the contractor might put on a show to make it look like they really care but as soon as your back is turned, that faked concern disappears.