Should sales staff interfere in application analysis and design?

Question

We're working on a kind of CMS, a fast, hosted, centralized website builder like Weebly. We also use Scrum development model. But there seems to be some problems here. Our sales manager always come to us, complaining about the design of the application, or UI elements, or stuff like that and hinder development process by making re-works again and again. Examples are:

1. Why do you have item actions like delete and edit in grid items? Just have list actions as a toolbar on top of grids. No item action.
2. Why red color? Use green. That's what people like.
3. Use tree for contents, not grid.

My question is really simple. Is it considered productive, or even normal for sales staff to interfere in application analysis and design?