Beware House Calls from Passing 'Jobbers'.

I've had two house visits recently from men telling me that my roof needs attention due to missing or damaged cement, it doesn't. Both times it was a small white vans with two men and sets of ladders. Although their actions are not immediately illegal, I would suspect they 'buzz' certain areas in the hope of finding inexperienced or naive people that would pay them for unnecessary work. My guess is that they are fishing for work in the present slump.