The short answer: the smell tells you where the problem is, and treating them all the same is why cleaning the machine so often changes nothing. Musty means mould and biofilm in the door seal, drum and detergent drawer. Sewage usually means a dry or blocked drain trap, and frequently not the washer’s trap but the floor drain nobody uses. Rotten eggs means hydrogen sulfide, which comes from bacteria, or from well water, or from a natural gas leak, because utilities add an odorant that smells of sulfur. If there are gas appliances near your laundry room and the smell is sulfurous, leave and call the gas company before you assume it is the washing machine.
Disclosure: this post contains affiliate links, and as an Amazon Associate I earn from qualifying purchases. If you buy through them I may earn a small commission at no extra cost to you. I only recommend things I would use in my own home.