Carlton's job is to visit foster families to determine if children under state supervision are being well cared for. Cuddy had recently agreed to act as Rachel's foster mother until she decided whether or not to adopt her and had to prepare for Carlton's visit.
Unfortunately, the visit was a disaster. Her place was a mess, her maid called in sick and, as a joke, House had hidden a dirty diaper in her purse. She was anxious when Carlton arrived and got more anxious as he went around the house.
As she tried to apologize and explain, Carlton told her not to worry and that her house was actually one of the better ones he had visited. He was satisfied by her attitude about the mess and knew it wasn't typical of their living conditions. He told her he would not have to visit for another year and wouldn't even have to come back if she decided to adopt Rachel.