It started off well but it's just slowly fizzled and will probably get worse once Makosi and Nadia leave.

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I think a main problem with BB11 and UBB is that the HMs are just too used to people walking in and out of the house. In the past HMs might have been bored just by themselves, and although it's a complete and utter p!ss take of the rules, the first time they had guests come in might have been fun for 5 minutes but now they're bored of that.
If BB just stuck to their guns and isolated the HMs with NO contact with the outside world, they'd focus more on one another and their emotions would bubble up. With new playmates just walking in all the time the HMs might as well just be sat in a cafe talking to any passers by and not taking in what they're supposed to be doing.