@Rebecca181
I couldn't agree with you more. The review system makes no sense. As a guest, I would think that 4 stars = Very Good, not only because that's exactly what I'm being told by Airbnb as I give my star rating, but because that's how it works in most of the hospitality industry.
Whenever I have occasionally explained it to guests (if reviews come up naturally in conversation), yes, they are astounded. I have very much been thinking about doing something along the same lines as you, i.e. a little written blurb left in their rooms. We shouldn't have to do this, but I think we have no choice, especially with the changes to the Superhost criteria.
At the moment, I am safe with my 4.9 average, but it would only take one crappy review to take away that security. After that, every 4 star review will hurt like hell. That's not okay. I try to do my best for my guests, but I'm also not going to live in perpetual fear of those 4 star ratings.
For example, a recent guest found fault with numerous things on his first day, almost as if he was trying to make a list of anything he could find that wasn't 100% perfect. The trouble was that the things he complained about were all clearly and honestly stated on the listing and there was nothing I could do about them. I was then in a panic trying to think of ways to appease him to avoid the 4 star review, but that review is inevitable no matter what I do because that particular kind of guest comes with expectations way beyond the anything I can deliver and regardless of the low price.
I wasn't so much annoyed at the guest (I'm not going to take it personally if someone thinks my listing is Very Good rather than Excellent), but I was VERY annoyed with Airbnb for putting me in this ridiculous situation.