Sorry Dan, fault, I had used the rules from the 2014 tournament, and changed the format a bit this year. I edited the rules a few mins ago.
Basic guidelines for voting are as follows:
1. You are voting not only on food, but also overall experience including price, service, location, etc..
2. If you have been to both of the competing restaurants in the match but feel very strongly about the one you have been to, feel free to vote for one of the restaurants.
3. If you have not been to both restaurants and don't feel strongly either way, simply vote pass.
Other than that, for the most part I trust the majority of people will vote based on personal experience, with the non-informed votes evened out between either restaurant. It's no way a perfect set-up, but the option to vote pass, which gets used quite often, is the best way I could think of to lessen this issue.