You aren't really any more likely to be infected by salmonella from eating a rancid raw egg yolk as you are from eating a fresh raw egg yolk. Salmonella is a bacteria that is carried by birds (such as chickens) as well as several other types of animals, and passes very easily through the shell of an egg. Under the right circumstances, salmonella bacteria can double every 20 minutes outside the chicken.
Normally, if a chicken is carrying salmonella, only 2-5 of the bacteria will exit the chicken with the egg, and it takes around 100 or more for your body to suffer illness from it. Eggs can go bad in your refrigerator and still not have that many of the microorganisms on them. Eggs can also still be perfectly fine to eat (if cooked) and have thousands.
Assuming that an egg leaves the chicken with just 2 of the bacteria, if the egg is cooled immediately, the count might go up to 3 or 4. If the egg is cooled in an hour, the count could go as high as 16-32, which is still not enough to make you sick. It takes nearly 2 hours for the bacteria count to reach a point high enough to make you sick.
If you were to eat an egg that was left uncooled for 2 hours, you would find that it was not spoiled at all. However, eating that egg raw could most certainly give you salmonella. With the fact that only 1 in about 20,000 chickens is carrying salmonella though, I wouldn't be too worried even then.
If you leave an egg in your refrigerator for a year and then eat it, you would likely find that it had spoiled, but the salmonella count would still be relatively low since salmonella does not reproduce well in cool temperatures.
Overall, I wouldn't be concerned.
Much of this information can be found on Discovery.com