Bad feedback is good, it helps you to understand why you are not selling and what you need to change to improve.

Instead, no feedback is very very bad. No feedback means that you have no clue why people don’t like your product/service. Even more, no feedback means that people don’t even care enough about your product to waste five minutes complaining about it. No feedback means that your product does not provoke any kind of controversy. And to me this is bad, very very bad.

As we say in Spanish (and possibly in many other languages but I couldn’t find the origin of the sentence nor the corresponding version in English): “es mejor que hablen de ti, aunque sea mal” which, approximately, means that it’s better people talk about you even if it is just to criticize you.

UPDATE: Two similar English sayings suggested by you:

Oscar Wilde: “The only thing worse than being talked about is not being talked about

Dave McClure: “people can love you, or people can hate you, just don’t be irrelevant”