I found this guy on Craig's List to do a simple replacement of a section of gas pipe. He came and did it. However, he left a giant oil slick staining my front walk - after I had specifically told him to be careful of the front walk. It was covered in leaves so I didn't notice it until the next day. I asked him to come and clean it. He became abusive, told me I'd never be able to find him or pursue this, and hung up on me. The damage is probably less than the cost of the work done, but this is someone I would never want working for any friend of mine.