Online Social Networking sites (OSNs) inspire the people to come close and increase communication easily. To make communication easily there are various online social sites that are available like Facebook, Twitter etc. which brought world closer. Social networking is one of the fastest media to spread the information. Users has a freedom to share their own emotions in terms of pictures, text etc. To do communication user have to create its account on respective web site then he/she may allow to perform various activities like adding friends, sharing videos and images. Social Networking Sites provides individual and separate space all users to post the status such a space is called Wall. But sometimes people post irrelative messages on a particulars wall which may cause a serious problem to user's reputation. To overcome this challenge some filtering criteria should be used. This paper has surveyed the details of existing filtering techniques.