When you create a map do you always develop the base map data? Probably not. That's why you source the data/work. What's the difference in this situation? My response was based on the assumption of professional honesty. If someone came to me with a project that they put together in a GIS and then cared enough about presentation to bring in a pro (or hire one of the many local carto tutors out there) to help communicate the message, I would consider that person to be thorough, not deceptive.
Now that is a really interesting question. You are absolutely right that in my eyes as a potential employer, the "shoe on the other foot" doesn't feel equal. But I don't run a GIS shop, I'm head of production (read "lead cartographer") of a map publishing company. Perhaps the difference is that cartographers (as opposed to GIS people) tend to think of data like a natural resource: we do as little original creation of base data as possible. I look at design sense in a potential employer very carefully, and if it were revealed in interview that someone's portfolio was not primarily her/his own design, I would be taken aback. I want to know what the prospect's design sense/skills actually are.
But, as I said, we aren't a GIS shop. And I can see how the shoe on another shop's foot (OK, that metaphor can limp offstage now) would in fact make sense.
Just when you thought the two cultures were merging...