Must be different fuel in Oz. Certainly my experience of engines in the 152 size needed plugs pulling before 50hrs. We have been operating a PA38 it lasts 50 hrs, even with leaning, quite a bit of lead in plugs.
This might hold merit as we had a problem with fuel from a particular refinery to do with dyes and tel causing a grime/slime in tanks and eating away at brass carby parts. Resulted in a lot of tanks and fuel systems having to be flushed with water voiding any warranty they might have had. There was also talk of WA AVGAS having some cause in fuel pump wear as opposed to eastern states, leading to a possible cause of engine failure and crash many years back.
Cessna 152 O-235-L2C and N2C are pretty solid engines, never really had any issues with ours if the engine was healthy and they almost always made TBO without much issue. A lot of the flying was circuit work and training area with students, lots of taxiiing and idling with only the odd case of fouling and we are talking thousands of hours a year between several 152s. To put in perspective for each hour of running time .3 was on average ground time, so every 100 hours airframe the engine was running 130 hours, that 30 being low power ground handling. Compared to the Arrow fleet where .1-.2 ground time per hour was average due to the navigation focus on its use. Maintenance was conducted on air-switch. I know early on C152 had a reputation for fouling issues, but I assume engine modifications and carby changes over the years, new plug technologies, may have remedied this. There were definitely more than one carby options for the 152 at least.