I'm fairly sure this must be ascam but....

We had a new Kitchen and were advised by the company to sell the old one. We advertised and got responses. One agreed to come and pick it up but could not give a definite time. It was all in the garage and unfortunately, on the given day we had to go out so left it unlocked. We were very lucky the people had come and picked it up and left all the agreed cost plus extra because it was clean.
We have since realised how very lucky we were.
The biggest scam where I used to live was men coming around and offering to tarmac your drive for a reasonable amount. They needed a deposit and a group of neighbours or so they said quite a lot agreed and they never came back keeping all the deposits.Luckily we never joined in.

Hithere, I understand that school teachers try to teach sceptical sense to all their pupils via stories and practical judgement. I do hope the teachers usually succeed!

Franbern, thank you for explaining it.

I knew when it was offerred me that it was too suss not to be a scam but I didn't know how it would have played out if I'd gone along with it.

Most scams are motivated by (a degree of) greed. Including the ones where some random grooms you into investing your savings for a higher rate of return than you could reasonably expect via other means. If it seems to good to be true it probably is.