How you could be ripped off while roofing your house

Have you ever bothered to see what the roofing height specification on your building drawing says? I guess not. How about climbing up there to measure if the roofing height is same as the one you are getting, which of course was quoted for and paid for? I guess not too. Now this is where a smart fraudulent roofer could rip you off, he can reduce your roofing height to suit his purpose and then pocket the balance on the wood as well as roofing sheets. I know most people are afraid of heights, so you can play right into their hands....lol...