You can't really guarantee there's no dullards anyway.
Sometimes someone who's usually a bubbly, loud, outgoing person suddenly finds themselves in the BB house and rendered speechless by the other bigger personalities.
Bonneh anyone?
There will always be people that stifle others which is one of the great things about Sallie being evicted after a week or so. The dynamic shifted slightly and we saw some other people. Gina opened up a bit more after isolating herself due to Sallie.