Forum Moderators: Robert Charlton & goodroi
Does that 403 error mean Google failed to cache the pic?
Yes - to be more precise, your server did not give the file to the bot. Whether the file makes it into Google's cache or not is the next step in the process. Not all that is successfully spidered ends up in the cache.
It's not the same as a robots.txt disallow (for example, it wouldn't work for a removal request) but the net result could be the same in time.