How to recognise a client with no potential before closing a deal

Every salesperson has experienced a client who, after some time, has made them think it might have been better if the deal had never happened. We are talking here about clients who consume too much time, resources, finances and energy, so that from a purely economic point of view they are not worth it. Luckily for businesspeople, you can recognise such cases before closing the deal and thus save yourself a lot of trouble.