A couple that hit close to home:
When you see the project budget, you realize that over half of it was spent on a Web designer to create a Photoshop mock-up of the home page—with no regard to whether that design is feasible. Or with any attention to the thousands of pages of content that will exist underneath that home page.
You are a Web developer. You open the ZIP file with the HTML documents the client produced for the site scripts you need to integrate with the Web application. And you discover the client’s HTML documents are all Microsoft Word files, saved in HTML format.