Low-resolution raster images would present a more difficult problem. This would require customer education with well-chosen, careful wording both in the advance instructions and in the preflight message, as preflight will be geared to pick up the problem and alert the customer to fix it.
Now let's tackle the biggest problem: proofing. Currently, there are three ways to show a proof. One, is the traditional, time-tested method of sending a hard proof to the customer. This is not acceptable because it is a costly, time-consuming interruption of the automated process. Another is a new and rather useless proofing concept of sending the customer a "soft proof" to view on the monitor after the file is RIPed and trapped. This may show trapping results, but makes no sense as a predictor of final color.