There's a popular English idiom, Don't judge a book by its cover. It means that you should not judge others solely upon their appearance or first impression.
However, it's helpful to know that this phrase was first said in 1800s. Back then, all books looked the same. Blend covers with gloomy hues, centered titles with the same fonts. When all are the same, it is fatal to judge them by their cover.
It is different nowadays. The authors and publishers have the full control over the covers of their book. They can paint it as unique as they want. It's yet another facade for them to express its message. And yet, if you don't do anything about it, then it's inexcusable.
The phrase still holds a valuable message. We should not approach the world with prejudice. But we should not shelter upon its wisdom. Don't expect the others to not judge you by your cover, especially when you and the everyone else have the full control over it.