If your egg is clean on the outside where does the bad bacteria come from? Because its not from inside the egg.

¯\_(ツ)_/¯ Don’t shoot the messenger.

While most bacteria including Salmonella are found on the shell itself, Salmonella can sometimes get inside an egg or it can already be inside an egg when it is laid.

https://www.canada.ca/en/health-canada/services/meat-poultry-fish-seafood-safety/eggs.html