Of course they'd try to get around this by ringing the doorbell, which is where the new Friend-or-Foe doorbell would come in. Using fingerprint-recognition technology, this doorbell would remember prints you'd told it to save in its memory as friends. The bell would ring whenever they pressed it. The bell wouldn't do anything when a solicitor pressed it.

We'd have to have a backup system for colder climes though, where your friends wouldn't want to take off their gloves to ring the bell. This is where the Doormat Stomper would come in. It could be set to respond to a number of stomps. Your friends would be given that number, solicitors wouldn't. If the doormat sensed the set number of stomps it would send a signal to the doorbell, triggering a ring.