Reading thru the comments and this one came up - from a previous contestant:

"As a former contestant on the show. and a proud winner I might add, the producers are VERY clear before the taping starts regarding properly speaking the words. No excuse for what she said, just a sad mistake that cost her cash"

It sounds like the contestants are told clearly up front that pronunciating words correctly is part of the game. 

What if NAT went by the same kind of rules?  Think about that one........    :)