I submitted a t-shirt design to a client, following their guidelines to a T.
Client: There’s a bit of a problem. Why didn’t you make the background transparent?
I double checked the file I sent them, and the background was indeed transparent.
Me: I did! I’m sorry, I’m not sure what could be the problem. Are you using the right program?
Client: I have it open in Photoshop now, and it’s not transparent. Fix it.
I resent the file, but also did some followup detective work on the original file. Turns out they opened it in MS Paint and saved over it, destroying the image. Which was, of course, my fault.