You, of course, would never do such a thing. But you might have a friend who would, or an evil twin brother…
To resize an ad to fit in another publication, you should change the dimensions of the document, then resize and move existing content as necessary. In this case, however, the ad creator took a simpler approach, electing to just change the document dimensions. What’s wrong with that?
Ah. Don’t look at the image and text; note where the black border indicates the trim edge of the InDesign page. Yep, that’s right. If this mistake had not been caught, the ad would have printed like this:
(This isn’t the actual ad. It’s just my quick example of what can go wrong.)
I’m trying to think of a rational (and charitable) explanation for this: Perhaps the designer had changed the document size, and was about to massage the contents, but was suddenly abducted by aliens. I post this not because I think this is a common problem, but because we laughed so hard when we saw it. And then we trembled in fear: oh, dear — what will they send in next time?