If you push air into the egg, something has to come out because of physics. The eggs can only hold so much. The egg whites and yolk are pushed out by the air that is inserted into the air. Basically you are replacing the egg guts with air. You can also use a clean syringe with hot water to clean the inside of the egg. I have a double sink in my kitchen. I fill the syringe and insert the needle into the egg. I then place the egg and syringe on the divider between the sinks with the egg pointing up. I then use the sink to push the water up into the egg. I try to shoot the water fairly wuickly. The jet of hot water cleanes all the residue out of the egg shell. It also takes the membrane off the inside of the egg. After a couple of jets of water, there really isn't much left to casue smelly eggs.