Lherkin...
...there are quite a few tricks of the trade to catch out these pseudo fitters. One is to wait until the fit has ended (they cannot posssibly regain full consciousness straight away) and then lift their hand/wrist over their face and drop it straight onto their nose. Their instinct will invariably be to to move their hand as it falls so as to not let their hand impact their nose = faker.
Another fave is to brush their eyelashes very gently with your fingertip - there should be no reaction whatsoever if they are truly in a post-fit ("post-ictal") stage.
There are some more ingenious and crueller tests I've heard of, including the theory demonstrated to me by a police officer that a truly unconscious person would feel no pain in his testicles. Funny that, as soon as they were grabbed the crim came around *very* quickly...

edit: Not advocating police violence - but this was an alleged kiddy-fiddler.
(emadex thinks the world will end on, Sun 16 Jan 2005, 8:24, Reply)