Were the eggs washed when you got them? If the eggs were washed when you got them, the bloom may have been scrubbed off by whomever you got them from. Make sure that your incubator is clean before putting in washed eggs.
If it smelled bad, you can nearly bet that there was bacteria involved. They are what makes meat rot and they are what give off the disgusting smell. If your incubator is clean and your eggs are 'clean' (not washed, but clean) then even dead chicks will not smell very badly.
As for what you measure with, the tool is called a hygrometer (not a hydrometer, those measure rainfall). You can buy them at pretty much any pet store, just have a look in the reptile section. If you ask, someone should be able to help you find it.
If you have questions and I stop reading this thread for some reason, please feel free to PM me.