Client: Please update these images on the site.
[I update images and confirm live]
Client: I can't see the new images.
Me: Did you try refreshing?
Client: Yes, I still can't see the new version.
Me: Did you try a ctrl-f5?
Me: Did you try clearing all your caches (explain at length how to find these settings - all of 3 clicks away).
Client: It's still the old version.
Me: Do you know if you're you using a proxy server?
Client: I'm not sure.
Me: Ask your sysadmin guys to flush the proxy cache - if they have one, they'll know what you mean.
[2 hours later..]
Client: Okay, they flushed the cache and it's still the old image.
Me: *tired quiet sigh*. Okay, I'll go see what I can do.
[I check with Billy boy and Jeff in London, NYC, and outer mongolia - ALL can see new image with no problems. I stall 'til the following day, assuming cache will clear.]
Me: Is it fixed yet?
Client: Yes, it's working now - what did you change?"
GAHHHHHHHHHHHHHHHHHHHH. OMFG. I am not your company's frikkin network engineer, get stuffed! :@