What am I risking by ordering and using those 1-2$ stm32 modules from Aliexpress?

I tried to Google around a little and it looks like these cheap modules that use stm32f103c8t6 use certainly fake parts. My question is how good these fakes are. I don't suppose they wouldn't work at all but I'm afraid of subtle silicon bugs that would cost me considerable amount of hair tore out my head while learning a new platform.
Because of that I'm asking for any experiences with these boards and other dirt cheap STM32 chips from China.