The "Scorecard" system of rating cleanliness of city streets estimates the fraction of total street length that is acceptably clean, based on selected samples. A parametric model combining 12 assignable variables related to the street cleaning programme of New York City, including workers assigned to street cleaning and tickets for Sanitary Code violations, was tested on a computer for several million combinations of reasonably assigned values of the variables. The results supported earlier studies based on regression analysis and increased the understanding of important variables. Street cleaners are far more effective per man hour in keeping streets clean than are agents writing tickets for violations. The models presented can be useful for planners in other cities.