Sweat doesn't inherently smell. The foods you eat affect how you smell, though not specifically because of your sweat. If you eat a lot of spicy food then your whole body will be releasing those aromas.

I think he's suggesting that the sweat is a problem whether it smells or not.

Ahhh, biologically it isn't - it's good to clean pores, keep you cool, etc..

Sweat on some parts of the body will keep you cool. Trapped inside a joint, not so much.

While sweat itself doesn't have much smell, stale sweat will smell due to bacteria. What you eat won't be able to change this.