These are some very situational "bugs" with the alerts. Situation one: If a user quotes a post in a section they cannot view, it will send an alert to the user who made the post. This requires that they know the post ID and the user ID of who made the post. Situation two: If a user quotes a post in the public from within a section that the quoted user cannot view, they will still get an alert for it, but when checking the alerts there will be nothing. Situation three: If a user receives a like from within a forum they cannot view, they will still get an alert (and a mysterious like), but no alerts will actually show when checking.