1. A computer implemented method for identifying business listings, the method comprising: determining, using one or more processors, a first frequency value of a business listing characteristic within a first plurality of business listings received from a first source, the first plurality of business listings being associated with a particular business listing context; determining, using the one or more processors, a second frequency value of the business listing characteristic within a second plurality of business listings received from a second source, the second plurality of business listings being associated with the particular business listing context; determining, using the one or more processors, a frequency differential between the first frequency value and the second frequency value; in response to the frequency differential exceeding a threshold differential, identifying, using the one or more processors, the business listing characteristic as a differential characteristic; and identifying, using the one or more processors, a particular business listing of the plurality of business listings as a spam listing using the differential characteristic.