TheMadScientist - 1:30 am on Feb 4, 2013 (gmt 0)
I don't know through what voodoo, but Google is showing images from by image folders that is blocked to its bot, following its own instructions!
I don't 'do' image search and I don't have time to really 'dig in to it' right now, but it likely has to do with them 'requesting the image on behalf of the visitor' and not actually requesting the image with their bot.
If it can be done, g### can find a way to override it.
To do it, you'd have to basically 'cloak' ... So, you'd have to discard the X-Forwarded-For header, check for any IPs in Google's ranges, then block those IPs ... They can't get around it that way (unless they throw protocol out the window like AOL used to, but they're not known to 'totally break protocol' even though they push the limits on things as far as they can) ... It's not a simple thing to do though and the 'back end' needs to be updated regularly, because as they add/drop IP Address ranges the blocking would have to be updated.
It likely can be done, but to do it you have to be technically proficient and 'all over the script' to keep it working.
ADDED: It might be possible by running image location requests through a PHP script and doing a reverse lookup on the 'down stream' IP Address if the referrer is not example.com to see if it's Google requesting the image on behalf of one of their visitors ... If you can detect it, then you can 'break it' but running image requests though a PHP page isn't something in everyone's 'bag of tricks', so it's probably not a 'large-scale' solution.