In my opinion 1-star rating is something that has terrible grammar. And you basically can't read the story due to how badly everything is phrased. Constant misusage of words, contradictions, and other similar stuff. In other words, when a technical aspect sucks a lot, I would give a story a 1-star or lower rating.
The problem with ratings and reviews is that everyone sees them differently. Except for haters, people might give one star simply because they don't like something. They don't look at how the said something is written the quality of it. If they don't like it, they put a 1 star or half a star. Some people don't give a low star rating no matter how badly something is written. Because they respect the author, who took his time to write and so on and so forth. Anyway, you can't think that everyone has the same thinking as yourself. That everyone uses ratings and reviews the same way you do. So don't think hard about them. Also, scribble hub notorious for the following thing. Almost all the novel that hit a trending or shows up in the latest series will get a fair share of one-star ratings. Even when you release a new novel with a single chapter, chances are high someone will give you a one star.
Edit. I also forgot to mention how I personally feel about this. It's not comfortable to get one-star ratings, so I try to ignore them as much as I can.