Guests can't post reviews on trivago because trivago is a hotel metasearch, not a booking site or a review site.
When travelers find and select a hotel deal on trivago, we direct them to the advertiser of that deal; a third-party booking site or hotel website. That's where they complete the booking process.
After guests stay at a property, they're asked to rate it by the booking site where they made their reservations. All reviews and ratings shown about your property on trivago are collected from those booking sites and third-party sources.
You can stay up to date on your online reputation by regularly referring to your profile's Ratings page.