I got this answer from the internet
Modern politics is dirty because of its leaders.When leaders,who make laws for country, use dirty words what can we expect from their followers.It is going dirty because every leader wants to get highest position in least time,everybody wants to get more and more money and status,That's why they do not get behind if they have to use dirty words and pose dirty allegations.As a result good people and women don't give priority to politics.Good people try to keep distance between their life and politics. We have today so much example of politician who are corrupt,casteist,rapists and criminals.And they easily become ministers, CMs .Now more criminals are coming in politics because they use illegal ways to win election and parties are indifferent of it.Parties just want to form government not non corrupt or good government.More surprising is that public too is indifferent of it.Public gives equal respect to leaders who are defectors and who are of clean nature.Eg.Gopal Canda. Public still like him and respect him while this person has destroyed one family.It is unknown to us how many families are being exploited today.
So our country can develop only if we have great leaders.And we have great leaders if we hate corrupt leaders and give opportunity to good people for coming in politics.