It's human to lie. Most of the time we can't even be honest with ourselves.

In case the context of the pre-election Bush quote on email I dug-up and posted isn't clear then this article may clear things up- Rove e-mails may be missing.

Democrats are suspicious that Rove and other senior officials were using the political accounts, set up by the RNC, to avoid scrutiny from Congress. E-mails already in the public record suggest that at least some White House officials were mindful of a need not to discuss certain matters within the official White House e-mail system.

Point is that apparently everybody from the President on down were hypersensitive to the idea that email was discoverable well before this scandal broke. Obviously they can't claim that anything was "accidentally" deleted when the President himself won't even send or recieve email because he's worried it will be part of "record requests."