All they are good for is to give unsuspecting homebuyers a warm, fuzzy feeling about buying a house. When we bought our starter home, the sellers paid for one. Totally useless. I had a clogged drain in the laundry sink in the garage and AHS sent out a plumber who wouldn't use the cleanout under the sink because it was too hard to get to. He wanted to go on the roof and go through the vent. He wanted me to sign a waiver stating that I wouldn't hold them responsible if his power snake damaged the brand new roof. I sent him away and AHS tried to make me pay for the visit. I told them he didn't do anything, so I wouldn't pay. Much discussion ensued and they made me pay, but then gave me a freebie for something else down the road. I don't remember what I used it for because it was about 20 years ago.

The short version: they are useless.