I LOVE SHARK TANK!
I have not seen the vietnameese version tough, im guessing it goes in vietnameese? if not i wil have tohave a look! Ofcourse one should be very prepared before entering the tank, but i feel alot of products wil gratly benefit from the exposure. your product/service should however be pretty unique and spectacular, as you say the worst thing that can happen is that the sharks puzzle away your buisness/product by beeing rough with a not finished or just badly designed item. Once again good luck! and i look forward to reading about your progress!