Singapore is by far the cleanest city I've been to on my entire trip! This cleansiness is largely due to the overwhelming amount of fines the "Communist" Goverment levy (which range from gum chewing/smuggling, spitting, littering, jaywalking, urinating in public, dancing in the streets, etc). However, in spite of this overcontrol of the public, I loved the city and ended up staying lot longer than expected!