Methods, systems, and media are provided for evaluating the quality of web-based properties for use as hosts of advertisements. Properties are automatically and dynamically evaluated for appropriateness of content, for instance, based upon extracted keywords and/or contextual information categories. Upon submission of an advertisement request, properties determined to be of insufficient quality are served a neutral advertisement, served a message indicating that no advertisement will be served, or served nothing at all. Advertisements determined upon submission of an advertisement request to be of sufficient quality are served one or more non-neutral advertisements as requested.