In yesterday's episode everyone could see that S's group members took positive pics of themselves and negative pics of Asim and his friends. Isn't that petty of S's team?
Also speaking of petty, look at how petty bb was when it put the dance floor on S's side. Obviously more people would be attracted to that side due to the dance floor being located there and their (guests) preconceived notions and instructions by the channel added to the bias.
Also another example of bias was when all the people bb put in charge of the pic task were S group member's. So obviously they would have been biased towards their own side.