Sometimes it's good to have a sincere feedback from a user that won't refrain to use the exact words that crosses his/her/their mind when a problem arises, and

Sometimes it's good to have a sincere feedback from a user that won't refrain to use the exact words that crosses his/her/their mind when a problem arises, and you can trust that the normal user from your app would use the same words and then look for another app. (Or site, for what it matters). Otherwise, how would you know that n users dropped off without telling you why?