@Wenyan2 Yes, just leave a response. When a guest has a review which mentions negative things, the way a guest responds can do a lot to let other hosts reading it get a balanced picture and not just automatically believe the host. We all make mistakes, both guests and hosts, no one is perfect, so acknowledging that and not being either defensive or aggressive in your response is the way to go.
With 13 good reviews, no one is going to decide you're a bad guest because of one review. I'm sure if a host had 13 good reviews saying the place was very clean and one saying it was filthy, you wouldn't immediately believe the outlier review.
So just be factual. "I might indeed have not managed to turn the heater off or secure the door. It wasn't intentional nor did I just ignore the instructions- the heater dial had to be turned multiple times and it was confusing as to whether it was off or not. And the door lock was one I wasn't used to, so I can accept that I might not have secured it. I'm sorry about those things and will try to be more attentive in the future or call the host for clarification.
As for the reported bleach on the sheets, I definitely did not use bleach on them, in fact, I did not wash them, I only slept on them. And I have never dyed my hair in my life.
I would have appreciated the host sending me a photo so we could figure out what may have damaged the sheets, before accusing me of something I didn't do, and sent her a message after seeing the review asking just that, but she never replied."
Something along those lines.
I can't see any reason the host would have to make up a story about the sheets being bleached, so I assume something did discolor them, she just falsely assumed it was bleach.
There are skin products and medications that can discolor linens and appear like bleach stains. I know that acne medication does that, and I'm sure there are some skin cremes, sunscreens, etc, that could do that, as well. As would hydrogen peroxide.