When we started using these bins, our council gave us two. A small one for keeping indoors and a larger one for tipping it into and putting out for them to collect. They also gave us one roll of compostable bags to put the waste in. On their web site at the time, it stated you could buy more bags from them direct or wrap up your food in newspaper before putting into said outdoor bin.
Our small indoor one is where we put all out fresh waste and that goes onto our own compost heap when full, they are not getting their mitts on that precious stuff. The only thing that really goes into the outdoor bin, wrapped in newspaper for convenience, is raw meat gristle scraps, bones, citrus and onion. It is collected once a week but as we don't eat much meat, our bin probably goes out once a month.
The other day, I was walking around the village when the food waste disposal man was picking up the bins and transferring the contents into a large dustbin he was pulling around. No neat little packets or bags of food were falling out and the smell was dreadful, like something had died!
Instead, pure smelly liquid based contents slopped out. Poor man.
I can only assume that most of the bins are probably not washed out afterwards by their owners so carry on smelling. I assume that due to the filthiness of the bins themselves.