There's another solution, which is that reviewers who find that their good review is being used to flog a substantially worse product (and in this case, the reviewer themselves gets to determine what is substantial) disown/update that review and/or refuse to review that manufacturer's products in the future.
that would require a lot of thought and tracking on reviewers part that I'm not sure most reviewers would care to do. Esp since it's for the benefit of others (amazon/manuf) and not themselves. If you pay them then you throw off the balance.
