I don't have a problem with 'em, they just stand/sit around the edge of the hall.
Although in one exam I had my ex-geography teacher take over invigilation half way through my exam, and she stood right behind me for like the last hour staring at me. Then two minutes before the end of the exam, she pointed at the bit of paper on my desk and shouted 'WHAT'S THAT?!?' - as if she'd only just noticed it.
Everyone turned round and I just panicked and turned to the front of the exam where it said we were allowed to bring in notes, totally stunned and speechless.
The cow had been trying to catch me looking at my notes, which I was allowed to have anyway, for an entire hour. *sigh*