On Monday, Jul 14, 2003, at 14:53 US/Eastern, Filip Van Raemdonck wrote:
I know I wouldn't remember everyone's face I have met for keysigning inthe past, or if I remembered the face I wouln't always be sure (s)he was claiming to be the same person back then as (s)he is claiming to be now.I equally wouldn't trust anyone else to do so.
I'd assume that if you signed the key due to seeing, e.g., a government-issued photo ID, you'd happily revoke the signature upon the presentation of the same.