[niggler]

"I almost certainly won't book an experience that doesn't have multiple positive reviews."

... even if they were spam or written by the venues themselves?

"For me, the reviews are the most important thing, and I doubt that I am alone in that."

Years of seeing these review systems gamed/bought for have left me jaded.

[realdlee]

I think if the review linked to the reviewer's profile that would help. Certainly there isn't a 100% way to prevent gaming reviews, but there are plenty of measures to keep people honest.