The bad fuel may have contained ethanol, and there may have been water in the tank, so now the fuel contains hydrated ethanol. Certainly you can't expect the engine to start well in that situation, since it changes the required air/fuel ratio and also will not flow through the jet properly.
Australia does not use the various ethers that are added to a lot of American fuel. They cause a need to add stabiliser to fuel that will be kept for even a few months. However some of our fuel does contain ethanol, which is hygroscopic and can cause trouble. Typically when it becomes hydrated it changes appearance, and to some extent smell, so if you are alert you can probably guard against what happened. However my preferred solution, for several reasons, is to avoid fuel containing ethanol. Water does not mix with petrol, it lays on the bottom of the tank, and in the bottom of the carburetor float bowl, typically stopping the engine from firing or running at all.
