A method and system for determining and notifying users of undesirable network content are disclosed. According to one embodiment, a method may include detecting an adverse content event corresponding to a given network information source, where the adverse content event occurs dependent upon activity of a given user with respect to the given network information source. The method may also include reporting the adverse content event with respect to the given network information source, detecting a reference to the given network information source on behalf of a particular user, and in response to detecting the reference, retrieving an indication corresponding to the given network information source, where the indication is determined dependent upon adverse content events reported with respect to the given network information source. The method may further include notifying the particular user of possible undesirable content with respect to the given network information source dependent upon the indication.