This is a quite as blog today. How to check when you read a real review on the google ad or not. This is how it works in most but not all cases.
1. Find company's reviews in Google
2. Click on a user name who left a review
3. It send to user's contributors page
4. Click on Reviews on the left
5. If you see empty list (because a user don't have review or marked as do not to show them. We can tell in 80..90% it's fake. especially if the company has lots of reviews and most of users that left reviews are closed reviews to see by public.