From their website:
"GDI has more than full time 75 associate Experience Specialists who anonymously check into hotels, including some of the world’s best hotels. Even now, as you read this, an Experience Specialist is in the balcony of a stupendous palace hotel, seated at a table, overlooking the city and sipping a glass of Chardonnay. After the main course, she excuses herself to make notes. Did the waiter offer chair and napkin assistance? Were the appetizers and desserts promoted? Was glass of wine refilled at exactly the right moment? Was the order taken within 10 minutes of being seated? What are the other diners doing and saying?
Our Experience Specialists are not "secret shoppers." Each one is experienced in the luxury hotel trade and can stand up to a SVP/VP or General Manager who asks them on what grounds they can judge the hotel. GDI standards are based 75% on service, and are precise leaving no room for speculation.
By the time the Experience Specialists checks out of the hotel, a detailed report, covering all areas of the hotel, with about 20 plus pages of narrative comments and more than 200+ digital photos, will be complete. The hotel’s score will tell the team where they stand in the select group of the world’s finest hotels."
Just be cool folks.