I’m sure I’ve read worse but one that stands out as making me question the time I put into reading it is Out of the Dark by David Weber. I go into it expecting a military sci fi, and for the vast majority of the book that’s what you get - aliens invade Earth and plucky humans resist etc etc. The aliens however have more reserves and air superiority so are slowly winning as the end of the book approaches, at which point you expect the main characters to pull a rabbit out of the hat and do something different. Except that’s not what happens.
spoiler
What actually happens is that Count Dracula appears out of (almost) nowhere and flies with a bunch of vampires up to the alien spaceships to kill the aliens, winning the battle for Earth.
I was definitely not satisfied with this ending, even if there was some foreshadowing earlier in the book that made sense after knowing this was a possibility in this universe.
I reckon Port Arthur is a solid contender with its low population of 251 (known for being the site of a mass shooting that led to significant changes in Australian gun laws). It is fading in name recognition as time goes on though, after all that was approaching 30 years ago and lots of people have been born since then.
My top pick however would be Bega with its population of 5013 and the name recognition the cheese factory has brought. It’s hard to go past a name that’s printed on cheese (and assorted other products now) in the vast majority of supermarkets across Australia, and they even export overseas to get a bit of international cachet.