Clients shouldn't listen to designers
It is sometimes true that a client has bad information coupled with strong opinions, and you end up with a demand to do something stupid and wrong. In these cases you should a) fire your client or b) do what they want, take their money, and deny that you ever worked on the project.
Something that is much more common (in my experience) is that the client wants it one way and the designer wants it another way because they have different goals and/or information. In this case the designer is often not "listened to" and the person with the money (the client) gets their way.
So here is my list of 8 reasons clients shouldn't listen to designers:
1. Clients sometimes know their business better than designers.
2-8. Clients have all the money.
Lets start with points 2-8. You need money to release almost any product, and the person who has that money is the client. They have the money because somebody gave it to them, usually because they did a good job spending some previous money or because they had rich parents.
They (the client) presumably hired you (the designer) because you have skills or insight. Some clients hire based on hard skills, like the ability to use Photoshop, which they equate with being a designer. You don't want these clients. They won't listen to you, they'll think they're smarter than you, and they'll end up doing whatever they want in the end.
If you want to do good design you should should find clients who hire based on your insight and soft-skills. The problem is that these people are smart. Smart people won't do what you tell them unless they understand why they're doing it.
So the designer who wants to be listened to has a conundrum: the people you want to work with won't listen to you, and the people who will listen to you are going to end up building a bad business because they aren't too smart. (That may be overstated. People who will always listen to you aren't too smart.)
Another way of stating this: Good design happens when smart people disagree.
When designers aren't listened to it's because they aren't making a good case for their position. Clients should never listen to someone simply because their title is "designer." A really smart business person never does anything because they're told to, they do it because they think it's the right thing.
Some of the best things I've designed were the result of high-stress projects where everyone questioned everyone else. The people respected each other and were ready to hear each other's arguments but never deferred to someone based in title or rank.