Never respond to them with the word "Yes". They will record your voice saying yes and then they will use it to say that you agreed to purchase a non-existent service from them.
There is a company called Open Business Directory that calls Businesses and says that they are YellowPages USA. They state that they need to verify the information in your online Yellow Page Listing. They will ask you questions like "is your address 123 Main Street?" They record the call without stating that the call is being recorded. If you say yes to any question, you will ultimately receive a bill from their company for $1188. They say that you agreed to purchase their directory listing service for your business. They target small businesses and threaten legal action if you do not pay their bill. You can check with the Better Business Bureau about reports of this happening.
That would still not stand up in court. That also is referring to business transactions, not personal transactions such as opening up credit cards, opening up bank accounts, etc. Also, you sort of scuttled your argument in that they ask for other information that is needed. So in reality, even that scam as you put it cannot be accomplished with one single word.
They can try to add third party charges too your phone bill and edit the recording to make it seam like you agreed to the charges making it hard to dispute. It was all over our news.