Recently I started to face quite many cases on my client projects when a visual designer on the team produces design that looks like wireframes produced by me, only colored. Perhaps, the obvious answer to my question is "don't work with this kind of designers". In most cases, however, the projects I'm working on are really interesting and challenging, so if I want to stay on the project I'm forced to work with whoever is on the team, so I better find the way to solve it.
I have talked to the teams explaining what wireframes are and what they are not and why applying some color to my wireframes is not a good design job. I have shown examples of excellent design jobs done based on wireframes. I have also switched from Omnigraffle to Balsamiq in order to produce mockups that look more like sketches hoping that this would force the visual designers to be more creative. It doesn't seem to work very well.
I know what it's like to work with designers who are able to (correctly) treat the wireframes only as guidelines for content, position, hierarchy, functionality, interactions, flow definition, etc. and do their magic to wrap it all up in a beautiful and elegant visual surface. That's the reason the opposite cases cause so much frustration.
Has anyone faced a situation like that? If yes, what worked well and what didn't assuming you tried to do something about it?