he who sells the lock, breaks the lock

Have you ever considered that the person selling locks can be the one breaking locks?

The other day a salesperson came to my door, trying to sell those locks for the main gate. He said something about a unit at a nearby apartment block had a break-in recently, blah blah blah, and while he was talking his eyes were constantly peering into my house, looking from floor to ceiling, walls to beams, scanning around like a security camera. This is the biggest turn-off.

Questions: How does he know there was a break-in if it was not reported in the newspaper? (perhaps he was the one doing it?) Why did he have to scan around the inside of my house? (a recce trip to see where the dough is?) And if I really need to buy a lock that does not require installation, why must I let you know where I live? Who knows if you have a duplicate of the key? Anyway it isn't that inconvenient to buy a lock from hardware stores.

I have nothing against (some) salesperson, but it doesn't harm to be on our toes.