GPT3 is certainly a valid thing to consider, but I think it has some weaknesses (e.g. there's an uncanny valley to them in terms of balance between relevance, novelty and coherence) and even the most sophisticated GPT3 cannot, by itself, mess with every marker (e.g. volume, distribution of content quality, conflict of interest between having generated low reviews and the ability to doctor review numbers, nuances associated with weasel words in real text vs in training set, variance in emotions/tone/interjections, reviewer consistency, aggregator reputation, etc)
Honestly, I don't see how to trust reviews if the reviewers have no skin in the game (either their reputation or money). If identities and reputations can be faked/generated at low cost, then we're back to just money. Honestly, one theory of advertising (like McD and bigC) is that they throw money at pretty ads to convince you that lots of people have given them money so they must be good... it's pay to play, but it's not completely wrong. Limiting reviews to those who have actually bought the item also helps, if you time limit/delay it and weight by the cost of shipping/stocking.