TLDR: Good marketers can be rare.
Marketing is, by definition, a profession where you try to get someone to do something they weren't going to do. Many people don't like that.
Good marketers are driven by user engagement and satisfaction metrics.
Bad marketers are often driven by sales or budgets and might do whatever it takes to meet those numbers, even to the detriment of applications and users. They have to hit those budget numbers. Think of the stereotypical marketer from the Dilbert comics. Bad marketers might lie or bend the truth. I've worked with several marketers who will lie to get what they want or to keep their jobs.
From a programmer's perspective, marketers might not understand the complexities of programming. "I want this change and I want it yesterday. What do you mean it's going to take 5 weeks to implement?"
From a designer's perspective, marketers might want what is flashy and attention getting no matter how much it litters a design and renders it unusable. Designers want what is appropriate based on the design hierarchy, established guidelines, or industry best-practices.
From the perspective of both programmer and designer, marketers don't always understand deadlines and might change things at the last minute or after it's too late. Bad marketers have no respect for the process of other teams because they only care about their team.
That said, I've worked with both good and bad marketers. I'm always sad to see a good teammate leave, no matter what department they work in. I've worked building marketing websites for 10+ years and love working with marketers.