When allowing house to bask in warm weather on a gloriously sunny Saturday morning, keep security door locked as defence against door to door sellers.
Note poor visibility through security door for those looking in, reasonable visibility when looking out. Use this to advantage, viz seller can only hear disembodied voice – you on the other hand can see the Time-Life logo on his pullover and know despite his vague motherhood pitch "Are you interested in your children’s future?" that he’s selling subscriptions to Time or encyclopaedias or some other thing you don’t want.
Recommend reject pitch as soon as practicable, eg as soon as he pauses to take a breath. Note that companies desperate enough to come knocking on a Saturday morning generally have useless products for sale. Rest assured your children’s future is secure without them.
Also note side-benefits RE: Mormons, Jehovah’s Witnesses, representatives of the Holy Church Insurance Vacuum-Cleaner Sales Premium Bond Corporation, etc.