Providing proof of certain assertions is important. But as @Lolest! puts it, if we go down the path of substantiation, we cannot restrict it to politicians but have to go the whole hog including accusations against business leaders, church leaders, journalists, Cecilia Mwangi etc.
For example, during the referendum, there were some very strong accusations made against church leaders on this site a lot of which was never substantiated. Some of us crying foul now were on that hate bandwagon then. It was simply convenient then because there was near unanimity.
All my friends are heathens, take it slow. Wait for them to ask you who you know. Please don't make any sudden moves.