Does fart always have an odour?

Passing gas: An odor is not always associated with passing gas. There are many variables like type of food eaten, the intestinal bacteria, putrifaction in the gut. Most times there is a smell associated.

Everything smells.: But every person doesn't notice every odor. Everything that comes out of or off of a person's body will smell like something. But it won't always be noticed by every person. Different people have different opinions even when they smell the same thing.