Yelp calls these "not currently recommended" reviews and they are way, way down on a business' Yelp page.
Scroll all the way to the bottom of a business' Yelp page, right after the last review.
Click the "other reviews that are not currently recommended" link. A few will show up, with a video at the top that explains why reviews are filtered.
It will only display a handful of reviews.
To see all of the filtered reviews, scroll down to the bottom of that list, and you'll see this link:
"Continue reading other reviews that are not currently recommended"
Click that link and you'll see the entire list.
At the bottom of that you'll see a list of reviews that have been removed for violating Yelp's content guidelines or terms of service. The content of these reviews cannot be read.