Unless the chin is sick it shouldn't have much of a smell at all, the poops should be dry to the touch and pretty much odorless, and they don't drink much so they don't pee that much for their size. How often you need to clean depends on what you use for bedding and if the chin is potty trained to pee in a pan or not. If you use fleece and they aren't pee trained you may need to wash the bedding daily, or at least a couple times a week. If they are pee trained just clean the litter pan daily and the cage once a week or so, vacuuming/sweeping up the poops daily. If you are using wood shavings (kiln dried pine or aspen) then you can normally go about a week between cage changes with very little odor even after a week.
The hay should smell like hay, not a strong smell but if you bring it up to your nose it should smell sweet, not bad at all. It's not a smell that fills the room like walking into a hay barn or anything. If you don't like the smell of fresh hay then I don't think a chinchilla is the right pet for you, hay is their primary food and needs to be available at all times.
It does stink if peed on though, if that is what you mean, so you do need to remove any hay that is peed on every day. It's best to use a hay holder so less hay is wasted, most chins wont eat hay once it's on the floor of the cage.