JesterMagic - 11:10 am on Jun 10, 2013 (gmt 0)
Thanks for the AppSpot Proxy information. I noticed them for the first time a few months ago visiting my site and ignored it thinking it's Google, a trusted site.
I just blocked them now (any HTTP User Agent that contains AppEngine) after seeing my content being index by Google using:
site:appspot.com "site text here"
I never have seen the content actually out rank me or even in the serps while checking keywords, etc.. but why take the chance (my confidence in Google is at an all time low).
I can't believe that Google would index duplicate content off of their own proxies. Can anyone give a reason why?