I let two door-to-door roofers get on my roof to clean my gutters for the incredibly cheap price of £40. Five minutes after they started working, one of them had 'discovered' that several of my roof tiles were mysteriously broken, but fear not! These roofers will fix my tiles if I pay an extra £100. Call me a suspicious bastard, but I'm 99% certain they broke those tiles themselves. Never trust dodgy bastards who knock on your door offering to do work for you. Everyone falls for scams, and anyone who thinks they don't is simply unaware of the times they have been tricked.