I look at it this way, the customer does not need to be burdend with art file setup. I have learned to accept every and all file formats and charge a setup fee of $65.00 for every new customer that has provided art, period. He needs to go about making the design (or at least getting it into final form) the right way. In the end, it's simply not enough for a customer to put together a vinyl graphics design in a vector drawing program.
FH was the only app that could get rid of the stroke overlaps. Those folks are lucky I have a Macromedia Freehand 10 license. They didn't understand why there was an extra design fee for correcting the artwork, so I just showed them a screenshot of the problem and got an "ohhhhh I see" kind of reply. Anyway, their new logo had all kinds of problems -the main one being lots of outline stroke effects that were not expanded into real paths and with all the overlaps removed on the expanded paths. I wouldn't take part in it (such contests are a waste of time for most working graphic designers). They ran a "contest" to get a new logo design -all just to get the new logo on the cheap. We recently did a rush job for our local Chamber of Commerce. As Derf said, appearances of all effects including all line strokes and letter outlines must be expanded and made "vinyl ready."
With certain effects in more recent versions of Illustrator in use the file will not import into most other applications. This also brings up the subject of educating customers about properly preparing vector-based art files.