Heh, I use S3 for hosting static sites only.
2 weeks ago they sent an email saying "[...] your AWS account xxxxxxxx has one or more S3 buckets that allow read or write access from any user on the Internet."
And I go "oh shit, what has write access set up?".
But nothing did. When they said "read or write", they meant 1, the other, or both. They just sent the same ambiguous email to everyone.