I'm the teacher that puts all the basketball sponsors on the scoreboard during games at the high school. The gymnasium scoreboard isn't exactly high-res, so image size is usually not a problem.
Except when a local car dealership (owned by a student's parent) sent us .gif that was 60 x 31 pixels.
Me: Hi! Could you send me a higher resolution version of your ad for the scoreboard? This one is too small and will show up blurry.
Client: That's okay, just use that one.
Three days later after the first home basketball game...
Client: My son told me that the logo is so blurry that you can't even read the name! I WANT THIS CORRECTED IMMEDIATELY.
Angry responses come like clockwork.