1 & 2. Poor Hygiene & Bacteria
Poor hygiene is less of a cause of stink as it is providing the right environment for stink to take hold. The name of the game here is sweat control. When you allow sweat to build up over a time, you've created the perfect environment for bacteria to grow. There's a normal amount of bacteria on your body that breaks down sweat when you work out. However, if you leave pools of sweat around (on workout clothes you haven't washed, or football pads in the guy's case) then you've created a breeding ground for bacteria. When the bacteria break down the sweat one of the by-products is that funky smell you wish would go away. So good hygiene comes into play in both getting excess sweat off your skin and your clothes to prevent the stink. Common examples of less than optimal hygiene include- Wearing the same shoes every day without letting them dry
- Wearing workout clothes multiple times without washing
- Working out then not showering afterwards