IF they have not provided private feedback to you about the cleanliness or value, reach out to them directly and ask. Why did they mark you down for these things? What can you do to improve for the next guest? Be open and non-defensive - respond after their feedback with a "thank you for sharing" message and that's all, even if your feelings are hurt. Try to listen with an open-mind to see it from their perspective.
You might learn that the guests "thought" a yacht would feel like living in an MTV video and it turned out it wasn't all that and a bag of chips - it was just a boat in a marina. There's not much you can do except try to set "guest-pectations" better in the listing and manage those during their stay. Tough to do for sure. You might get some real feedback that you can do something about - maybe the head could use an airfreshener for the land-lubbers who aren't used to bathrooms smelling like, well, toilets (I'm not suggesting your bathrooms smell, I'm just being colorful). Or maybe that thing that doesn't really bother you, really bothers your guests and you can fix it, like fingerprints or something you just don't see anymore living there.
What you will learn is a lot more about the guest than what you can do to change things. We once got a 3 for value because we didn't have orange juice available in the morning. For him, this was a horrible mistake and staying with us just wasn't worth it - all because we didn't have juice. So I learned something - this guy likes his juice but he didn't bother to tell me at any time he just absolutely had to have juice to make his stay 5-star. Do I buy juice now? Nope. It was irrational. We've also noted that several of our lowered "location" scores were because our home is fully renovated, others on our street are not - YET! So while we see the improvement, fully understand the changes taking place and love the diversity of our neighborhood, sometimes our suburban, middle-class, HOA-loving guests with their McMansion somewhere in Middle America do not. We can't paint every house and you can't clean up every dock or boat. There is little you can do about this lack of openness in people's eyes.