Sounds like he needs

a) a bath. Wear gloves and long sleeves, bathing a cat can be pretty challanging, although many Maine Coons just love water!

b) to be put on a diet. If his rear end is smelly, that's a pretty sure sign that he's too overweight to clean himself, which is NOT healthy.

Even for a Maine Coon, 30 pounds is tooooo much! The breed book says they can weigh "up to 18 pounds" for a "large" male, and my brother's biggest cat - actually the biggest cat I know currently, Pippin, a probably Maine Coon or mix, was a couple pounds overweight at 20 pounds. (So he got put on a diet.)