What are the odds?

Saw this on BBC3 the other night and laughed so much my throat hurt, so of course I looked it up immediately afterwards... So what are the odds that almost every single ten-star review would come from someone who (a) signed up for an IMDb account within weeks of the film's release and (b) hasn't felt it necessary to comment on or rate a single other film in the intervening two years? I'm thinking they would be very, very long.