You might NEVER get feed back from your audience about what you are doing wrong.
Sometimes, you will get hints.
If a visitor did buy a product and what they get does not match what they expected, they might tell you.
However, simple visitors will not take the time to give you feed back on poor design, broken links or needed features.
You need to find out for yourself and TEST your website from a user's perspective + sit down with testers and see how they experience accessing your site.
If you have a website, it is YOUR job to do this testing rather than hoping that visitors will step in and tell you what to do.
Got that? If you care for the user's experience, this is ESSENTIAL!