Link to their website:
Below is quoted from their "Gun Marking Guidelines" page:
"There will naturally be some uncertainty about whether any particular location actually represents an unsafe gun situation, and again, the general guideline is that you should mark any location about which you have a gun related concern, while trying to provide enough extra information for others to make their own determination about safety. Try to keep the following warning signs and guidelines in mind when determining if a local gun owner may present a threat to your children or your community. While the remainder of the guidelines are fairly obvious cases for marking if true, it is important to remain clear headed about your assessment and avoid misunderstandings. Users of the Walkingtools Gun Geo Marker hold the responsibility for the quality of the information the system presents (while remaining anonymous), so try to be as clear about your concerns as possible."
jrs - emphasis is mine. Just remember, any data you enter is anonymous.