How can you tell if milk is bad, when you got a broken nose?

So, my nose has been broke a few times. Funny how impact from fists and elbows will do that. Anyway, I can't ever tell if milk is bad. I smell it and it always smells kinda bad to me. How can you tell? Is there a certain level of funk that you reach? I guess you know for sure if you have big chunks (any chunks really) in the milk. I just wonder if there could be a machine that helped me out. We have machines for everything else. Why not a Sniffer-Matic® (see I trademarked it, now I'll make millions!). It could smell all my food and tell me what is good and bad. That would make cleaning out the fridge a breeze! What about at a party? How cool would that be? Just adjust it for body odor (turn knob) and now you can embarrass all the funky people in the world. That could get you beat up. Running around using some machine that sniffs peoples arm pit/ butt may not be a good idea. Anyway, Sears, Maytag, Kenmore, some appliance place, make it happen!