Customer Survey Dissatisfaction.
Modern life is replete with customer satisfaction surveys impinging on seemingly every digital, telephonic or physical interaction and CEOs citing how x% of their customers were "either satisfied or very satisfied" with the service they received. It's also replete with dissatisfied customers.
So before you undertake one of these exercises, perhaps you should ask what its purpose is. Are you seeking to elicit genuine information or are you box-ticking? Do you want to learn or to obfuscate?
What does satisfaction actually mean? We all have different satisfaction spectra determined by our previous experience, so it's pretty meaningless to survey it. Even if we were consistent in our appraisal, there's the timing issue. Our satisfaction is dependent upon our happiness relative to when we're surveyed because memories fade.
Crucially - the dissatisfied customer, the target you're really trying to find will either have forgotten it happened or more likely will no longer be a customer and their dissatifaction will not be captured.
The key to increasing customer satisfaction is to improve your product and service. It's not to bias a survey.