At some point, it will likely happen with every client. Either because they passionately believe in something or have chosen to exert control, at least once in every campaign you may have to talk your client out of making changes that could derail the success of their campaign.
When a client is adamant about a particular approach or element of their campaign, they can be difficult to reason with, even if you have a long history of success under your belt. Client negotiating is a key skill for marketers to develop and — believe it or not — there are ways to talk a client out of going down the wrong path.