If you had issues with your app when it was first released and you got some negative reviews, it can be difficult to overcome that obstacle. Once you have made the necessary changes or improvements to your app, you can get started working on overcoming those bad reviews.
Many people have found that paying for reviews is the fastest and easiest way to get past unwanted reviews. This is because the 5-star reviews will begin to outnumber the bad ones and drive the average ranking up. In addition, since the positive reviews will be newer, they will generally be displayed toward the top of the list so more people will see them.