Thanks! Yeah, that's really the most important question. There are a couple of answers.

Longer term, we're hoping that the best / most helpful / most genuine reviews are discovered and promoted by market forces on the platform, including:

In the short term, we have our own moderation processes (and will be building more):

There are other technical solutions too that punish / disincentive spam and bad actors. For example the 'Web of Trust' system that Stacker News has implemented here!

In short, I think there's a whole host of things we need to be doing