It could be a violation of these:
What's not allowed
Amazon is pleased to provide this forum for you to share your opinions on products. While we appreciate your time and comments, we reserve the right to remove reviews that include any of the following:
Objectionable material:
• Obscene or distasteful content
• Profanity or spiteful remarks
• Promotion of illegal or immoral conduct
Promotional content:
• Advertisements, promotional material or repeated posts that make the same point excessively
• Sentiments by or on behalf of a person or company with a financial interest in the product or a directly competing product (including reviews by authors, artists, publishers, manufacturers, or third-party merchants selling the product)
• Reviews written for any form of compensation other than a free copy of the product. This includes reviews that are a part of a paid publicity package
• Solicitations for helpful votes
Inappropriate content:
• Crucial plot elements (unless you offer a clear "spoiler alert")
• Other people's material (this includes excessive quoting)
• Phone numbers, postal mailing addresses, and URLs external to Amazon.com
• Details about availability or alternate ordering/shipping
• Videos with watermarks
• Comments on other reviews visible on the page (because page visibility is subject to change without notice)
• Foreign language content (unless there is a clear connection to the product)
Off-topic information:
• Feedback on the seller, your shipment experience or the packaging (you can do that at
www.amazon.com/feedback and
www.amazon.com/packaging)
• Feedback about typos or inaccuracies in our catalog or product description (instead, use the feedback form at the bottom of the product page).