I grew up in a household where meat/chicken/etc. was defrosted on the counter...sometimes all day depending on how big the meat was. Never got sick from that habit. Leftovers went into fridge when meal was over and used within a day or two. They were reheated on the stove or in the toaster oven (my mom loved hers!).
In my household, defrosting done in the microwave or slowly in the fridge. Leftovers? If not looking like a high school science experiment they are fair game.
Only thing I am very careful about is any food containing mayonnaise that may have been sitting without refrigeration.
My DH recently had a question: does sour cream "sour" when it goes bad? Hmmm...that's one to think about.