For good or ill, at the table, the GM does not have much time to grab the attention of the players. Whenever I see a published adventure with multi-paragraph boxed text that is intended to be read aloud, I cringe.
Blame smart phones, the Internet, television, that gosh-darned rock and roll music, radio, whatever you want, but at the table your players have limited attention spans. You have, at best, three sentences before the players lose interest. Now any interaction that the players have can reset this three sentence time. So rather than generic NPC # 6267 spouting off a novel-length explanation of the Dread Lord’s personal history, make it a dialogue. Have the players ask questions and get answers based on the questions they ask. Maybe they will bribe, threaten, or cajole the NPC.* What was an info dump is now a roleplaying opportunity. Make them think they are getting information they would not have otherwise received.
The reason I bring this up is that due to the fact that players have limited attention spans, we GMs need to make the best of use of language that we can. Each sentence we say should be viewed as a resource, much like an arcane magic-user considering whether or not to cast a spell. Once that sentence/spell is used, that is one less sentence/spell you have!
Therefore, GMs should look at their vocabulary. Find ways to optimize it. Even if you are not a professional adventure designer, you will undoubtedly have some “boxed text” of your own that you use to describe a room, person, or situation.
If I may paraphrase what Robin Williams’ character said the movie Dead Poets Society, remove the word “very” from your vocabulary. The NPC is not “very tall”, he is “towering over the party”. The lich is not “very evil”, it is “vile”.
You should also find words that stir emotion within your players. As long as the emotion is appropriate to the situation, encourage it with your word choice. If you players should feel disgust, use words that sound “gross”.
Consider these two examples:
A) The room smells very bad because there are a lot of dead people on the floor.
B) Upon entering the room, the putrid smell of decay assaults your nose. Upon the ground, you notice the fresh remains of what appear to seven humans, their bodies arranged in the profane symbol of the Serpent God.
While this second example uses more words, it does evoke more of a reaction. Which room would a character feel more uncomfortable in?
Finally, a caution. Do not pull a random word out of a thesaurus as a replacement for a more common word. Make sure you are using it correctly!
* Hopefully not seduce!