He should substantiate his statements with evidence. Otherwise should get into mud, to do mudslinging on someone.
However, both Atal Bihari Vajpayee ji and LK Advani are politicians and their profession does not give them immunity from mudslinging!!
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The first family keeps a lot of different kinds of pets for the different utility they provide. Diggy's specialization is to do exactly the kind of things which you have mentioned.
Yesterday I watched him on Karan Johar's programme Devil's Advocate. This gentleman was clueless as to how to counter the allegations against the royal son in law. So he resorted to just two or three answers ie where is the proof?, it is a private matter between Vadra and DLF and everything was done officially by a very efficient Haryana govt. To make matters worse for him self and his he kept laughing in a very sheepish manner. He does not realize that public does not bother about what politicians say but what their body language says. I think he ended up doing a great dis service to his leaders.