What actually is most likely going on here is one or a string of people independetly are periodically doing this because they find your reaction amusing and you keep feeding them.
Regardless, a low rating doesn't mean they think they can do better. Those thoughts are totally unconnected. It means at the least they didn't enjoy it, or they thought that other people on the site had done better.
I don't really see why this occasional bit of trolling bothers you so much when most of your posts get an automatic 9 or 10.
