For instance, there's a rule in English that dictates the order in which adjectives must be arranged in modifying a single noun. Break it, and while the sentence is still comprehensible, it feels wrong, as if the words were dancing around in a mad boogie. Or the sentence were composed by a non-native speaker trying to appear fluent by speaking rapidly without having the mastery to back it up.
Interestingly, this is not just a rule of formal speech and writing. It's also followed in the most casual and colloquial speech -- yet some types of violations can be turned into non-violations by treating the out of place word as part of a compound word. For instance, in the article there is the example of "green great dragon" as a violation of the adjective-order rule. However, for someone familiar with fantasy literature can imagine a world in which there were a specific type of dragon known as a "great dragon," which comes in various colors. In that specific Secondary World, "green great dragon" would become a legitimate construction, although the author might well decide to use capitalization to show that "Great Dragon" is a specific type or tribe or nationality of the draconic kind (especially in a situation where dragons are sapient and have personhood on the same level as humans).