The document is a 2 column layout in indesign -- a header at the top of one column, a chart at the top of the other. They are mechanically aligned.
Client sends an email telling me to check the alignment. I do, it's fine. Next round of revisions, client prints out pdf and freehands a rather wavy line to show that they aren't aligned. I triple check, they are. Next round of revisions, the client takes out a ruler and draws a line (rather dark and angry looking, I might add) to show that they aren't aligned. However they are holding the ruler at a slight angle, as evidenced by the fact that the line doesn't touch all of the ascenders towards the end of the header.
Finally, I realize that I will have to directly address this concern in a way to completely shut down complaints. I take a screen shot of the document with the guides on. I send this in an email with the note that they are definitely aligned.
Client sends me back "Thank you so much for sending the guides to show me that they are aligned. The pdf must be distorted."