haha. I wonder if Amazon invented this useless tag
to make people doubt reviews by those who didn't buy at amazon:
What's an "Amazon Verified Purchase" review?
When a product review is marked "Amazon Verified Purchase," it means that the customer who wrote the review purchased the item at Amazon.com. Customers can add this label to their review only if we can verify the item being reviewed was purchased at Amazon.com. Customers reading an Amazon Verified Purchase review can use this information to help them decide which reviews are most helpful in their purchasing decisions.
If a review is not marked Amazon Verified Purchase, it doesn't mean that the reviewer has no experience with the product – it just means we couldn't verify that it had been purchased at Amazon. They may have purchased the item elsewhere or had some other interaction with it. If we could somehow validate their experience with the product, we certainly would. The Amazon Verified Review label offers one more way to help gauge the quality and relevance of a product review.
How can I make my review an "Amazon Verified Purchase"?
When you write a new review, you will be given the opportunity to mark your review as an Amazon Verified Purchase. If the checkbox doesn't appear, we were unable to verify you purchased the item at Amazon.
If you wrote a review for an item you purchased at Amazon previously and would like to mark it as an Amazon Verified Purchase, simply edit your existing review and the Amazon Verified Purchase checkbox should appear. After checking the box and saving your review, your review will immediately be marked as an Amazon Verified Purchase. You can also opt to mark all of your past reviews for products purchased at Amazon as Amazon Verified Purchase reviews using the corresponding checkbox during review editing or creation.