Sure, but then that reduces the effectiveness of such techniques by 1/4 or 1/10, while still carrying the risk a secret shopper finds it.
a couple hundred or a couple thousand 5-star reviews is plenty anyway. It's the old "don't be greedy and get noticed" thing.
plus, you can get an initial bump from taking another item and changing the name, or buying from one of the "free item for positive review" services. The fake reviews just need to be enough to offset the ongoing bad reviews. 1/10 boxes is fine.