There was a time when a knock at the door usually meant a neighbor stopping by, a friend visiting unexpectedly, or a package delivery. Today, many homeowners (especially seniors) approach unexpected visitors with far more caution. Law enforcement agencies, consumer protection groups, and home security experts regularly warn that scammers, thieves, and fraudsters often use door-to-door tactics to target vulnerable individuals. In fact, surveys show that many older adults now intentionally avoid answering the door to unexpected visitors because of concerns about fraud and personal safety. And they are right to do so. In some cases, not answering is the best option. Here are nine instances where it’s smarter to just ignore the doorbell.