Me to client: Can you send me that logo in an .EPS format?
Client - copies and pastes .GIF logo in Illustrator > Save As > .EPS and emails it back to me.
client: I can't get this image to upload to my website
me: that's because it's a BMP, you need to upload a JPEG
Client changes the extension of the file from .bmp to .jpg to "convert" it
here's one I've had.
me to client: Can you send me a higher resolution of that image (instead of the thumbnail)?
client resized thumbnail to 10" 300dpi in photoshop, saved as a hi-res tiff. and sends it back to me.
That happens all the time on these forums, especially when people wonder why their Favicons don't work.