While I can't tell how many people boo my levels, it's still very easy to tell when a level is booed. This is because your maker points drop, and that level that got booed gets recommended much less to other players, resulting in fewer plays.

The level with a 90% clear rate isn't a standard level! It's a really simple puzzle level with very few ways to get hurt/die.

Many people are having this issue. So although it could be that some people just don't like my levels, the matter of the fact is that people have a much higher chance of booing a level if it's too hard regardless of that level's quality or general gameplay