Also, why would the spreadsheet be calling these images every hour. Did you have the spreadsheet open? Does google do this call even when no one is viewing the spreadsheet?
Plus you cannot put a robots.txt at s3.amazonaws.com so if the url is accessed through the https://s3.amazonaws.com/.... url, the robots.txt will not work.
Yes, that would solve the issue of not being able to have your own robots.txt file and I did not know about that. On the other hand, Feedfetcher would still ignore the robots.txt
I disagree. Feedfetcher is no different than a browser: it fetches the URL the user inserted, nothing more (unlike a spider, which discovers URLs by itself).
I believe the parent's point was that, for the HTTPS scheme, you can't use any alternative CNAMEs, because they won't match the key S3 serves--so if your site is designed to be HTTPS-by-default, and is attached to an S3 bucket, putting a robots.txt in it is moot.
Not on S3, no.