We can ask them, we can send them feedback forms and number scoring to rate us on. But there is a problem that customers won’t tell you the truth.

I’m going to take this apart a bit - firstly if you are the business owner, a canny customer might think they can take advantage by not seeming overly pleased with the product or service. Their aim might be to get money back, or a future discount or some other advantage. 

Secondly the customer might care about your feelings and not want to offend you or the problem might be too embarrassing to tell someone they know particularly if you have evolved a good relationship with them. 

Asking them if they are likely to recommend us to someone (net promoter score) doesn’t give us very MUCH truth and isn’t very useful as it doesn’t tell you why.

You might not know which questions to ask to get useful information from them or how to phrase it in a neutral way. 

The effort of replying - especially writing out the answers or filling in a form online isn’t much fun and there is little intrinsic reward - so it gets ignored or only the minimum is proffered.

Secondly you might not understand the truth your customer or team member is trying to tell you. Words are only an approximation of what is conscious and there is much sub-conscious activity taking place too. Unless you know behavioural theories then you are unlikely to understand enough to make full use of the answers. 

Which is, of course, where I come in. Because I am independent there is no advantage to be had to the wiley customer. One to one questioning in conversation form is more natural and intrinsically rewarding for people and I can get more clarification on unclear responses. Moreover I can relate their answers to behavioural theories and reveal much more information.