[itronitron]

a colleague of mine pointed out many years ago that the slogan is not in fact 'Do be good' but rather just 'don't be evil'.

[tim333]

Be good is much more grey - all actions probably have some good but are not perfectly good. Whereas evil stuff is hopefully unusual.

[kibwen]

There's the fallacy, then: there's no law that says that evil actions are inherently notable or eyebrow-raising. It's perfectly possible, and indeed common, to do evil by doing nothing at all.