Client: I am sending you a file for you to prepare for print on billboard. 18.3 x 4.6 meters. Got it?
The client sends me an email with two files: one is a heavily optimized (i.e. blocky) 100 x 150 file with unreadable text called THE_DESIGN.JPG; the other was exactly the same, except saved as THE_DESIGN.PDF.
Me: I’m afraid these are completely unsuitable for printing at such a large size. You need these re-designed and in vector format.
Client: But why?
Me: The file you sent me is suitable to print at about the size of your thumb. If you tried to write your company name, address, phone and email on your thumb, and then stretched that to 18.3 x 4.6 meters, do you think you could read what you wrote?
Client: Don’t be ridiculous.