When using a scale in a customer survey, use a scale on which the customer can easily orient himself. You as the survey creator are the expert in all the subtle descriptive terms of your offering, but your customer is not. That means you need to make it easy for the customer to be able to give you true feedback. Do this by providing a reference point in the scale that he easily recognizes.

An excellent way to create that recognizable reference point is to assign the middle-point of the scale as referencing the quality of the product or service as they have currently received it. From that orientation point, the customer can then easily provide graduated feedback as so many points less or more from what he knows confidently to have experienced. Be careful though not lead the customer to parrot back what he thinks you want to hear. Provide labels that indicate preference rather than an indication of what you do or don't like as the vendor.

An example in this screenshot of such a scale is for a specialized skin care product. The vendor wants to know if the customer would like it harder or softer to the touch than the one they have currently purchased and tried. The middle point of the scale references the product as they have currently experienced it.