Definitely.

Yelp will delete or make much less noticeable the bad reviews about businesses IF that business pays them.

Once I hired a REALLY bad contractor after looking at his Yelp reviews, and I didn't know at the time that Yelp hid his bad reviews - you had to click another small link at the bottom of the page to view his bad reviews. All his positive reviews remains up on top and visible, so it looks like he is overall good. The contractor I hired turned out to be a NIGHTMARE.

Yelp should be shut down - they truly do use extortion against businesses.