Oh my... Suzaku is quite dense. The hair totally gave it away and yet he didn't recognize C.C. But this is anime... A little costume change can make a difference. Let's see some examples... Ermm...

In Powerpuff girls Z, the girls only changed their clothes, but nobody knows their true identity other than the mayor, professor. Sailormoon is another thing. Anime characters can't even tell if a person is a girl dressed up as a girl despite the girly features.