That wasn't the intent. Cloth masks catch some bacteria/viruses, primarily in the mucus/saliva droplets that they do stop, which is where most of the antigens are carried. However, they don't seal to your face. They do deflect and slow the air expelled when speaking and coughing so that it doesn't travel as far forward, reducing the risk of spreading whatever you may have.
What he said. Also what you smell when someone farts is gas. A mask that would prevent you from smelling that would probably stop you from being able to breathe as well. This is about stopping / slowing the fine fluid particles that carry the bug so you don't spread the bug around as much to others. If you want to know if masks work just look to the countries where 80%+ are wearing masks and see how the outbreak is going (South Korea for example).
Ummm, they test the fit of a mask by putting a hood over your head and spray a gas, if you smell the gas then the fit fails.
^^^ When they start testing the fit of homemade cloth masks that way this may be relevant. They don't even test surgical masks with that rigor. But this thread is about pictures, not debating about masks. Obligatory Picture: