Definitely the Boganic losers in the first season treating a female housemate like shit for not wanting to go nude in the shower (forgot their names). Sad fucks, just wanted to see her nude, and insulting her for not doing so (wow).
Back then BB surely loved to add in disrespectful, rude people...
If a girl says she doesn't want to go nude in the shower in these days BB, no man would complain. They would respect her.
Oh yes, also Travis from 08. He was treated horribly by the male bullies - Rory, Nobbi and their pet Ben. The guy's bad treatment was physical in nature - he was scrawny and short, whilst those 'men' were built and tall. They treated him like how high school bullies would treat their victim - pushing, shoving, etc.
Estelle's 'bad' treatment was rather subtle in nature and not that terrible. It's just that it was recent, so people make it a bigger deal. I actually like her, but I don't like it when people make it a big deal when it comes to her treatment. The housemates were just competitive in nature, so they made a strategic plan to get rid of her - they saw her as a threat as she never got evicted. It was all strategy - Welcome to Big Brother.