I don't think Estelle was bullied.
Estelle had a game plan to be the outsider & get the sympathy vote.
It worked a treat for most of the series, but died when it really mattered.
There is no need to argue over semantics. Bullying or not, the fact is that Estelle was treated like shit by the vast majority of Big Brother 9 housemates, purely because they thought she was strange, and that they deserved their place in the house above her. Perhaps you don't consider social isolation to be a form of bullying, or that Estelle strategically sought out her status as an outcast to win our sympathy. Fair enough, but when I watched BB9, I saw attempt after attempt of Estelle trying to integrate herself within that group and always meeting rejection. Why do you think she so naively accepted Michael's advances when he made the bizarre move to hook up with her? She was very naive, and sought out whatever semblance of belonging to a group she could get. Ava. Michael. Remember the Layla and Sam alliance (which lasted about a week before Layla was back to hating Estelle's guts again...)? When you're met with such open hostility from a group like that, you'll take whatever rare scraps of kindness they throw you.
I don't feel the isolation was brought upon herself. Up_All_Night brings up an excellent example of this, where Ben and that vile wench Stacey tried to think up a way of splitting Ava and Estelle up. Estelle was "isolating Ava from the group" in their minds. Incidents such as these paint a picture of a group of people doing their best to isolate Estelle from the group, simply because they saw themselves above her - in their minds, she was just so lame, and they were just so awesome. They were above associating with her. They didn't just do it to her, either. Anybody who was deemed too lame to associate with this group of narcissists was deemed a meeper, and treated with as much hostility and disdain as possible, lest people start to think that they are LAME BY ASSOCIATION. Such was the entitlement of these housemates - they deserved Ava more, they deserved to remain in the house more than Estelle, how dare these MEEPERS interrupt THEIR conversations with their EXISTENCE.
There's a reason I hate so many of the Big Brother 9 housemates - when I watched the patterns of behaviour exhibited in that house, I didn't see very nice people. There was a clear group mentality in that house, and for no real reason - never once did I hear a well articulated reason from a housemate for why they hated Estelle with such zeal. In the diary room, the housemates even admitted that there was nothing really wrong with Estelle. The excuses were always "she's annoying", or "she's weird and acts strangely sometimes!". Boo fucking hoo. Learn to live with it, stop thinking you are above everyone, and learn to treat people as human beings. Even to this day, when Ben brought up the topic of Estelle in his housemate thread and why she was such a bad person who deserved it, he still can't articulate why. It's always a vague hint that she said or did something horrible, and that she's such a horrible person for this reason, but he won't go into details about it, because it would be "petty". THEN WHY BRING IT UP IN THE FIRST PLACE? Insinuating, to this day that his behaviour was somehow justified says enough about how petty he still is. The truth is that Estelle was just a normal girl, who they started a hate campaign against because they thought she was lame and that they were above her. When she survived against people they deemed better than her, they got pissed and the hate intensified. Simple as that.
I recall hearing Zoe has since apologized to Estelle after the show for going along with the group and treating Estelle in the way that she did. I think that says it all - a person like Zoe was willing to go along with the group mindset, for no reason other than to belong to the group and avoid social isolation herself. I find it telling that once she was removed from the group situation, and no longer felt that need to conform, she suddenly realized that "Oh, Hey, Estelle's actually not so bad... why was I treating her like shit?"
As
@up_all_night stated, it's a real shame that so many people were blinded by the superficial charms of these housemates, and how many people will justify a person's shitty behaviour simply because that person possesses a few traits that seem to hold high social value.