Yeah, I used to go to the gym too. Vinegar kills almost all bacteria purely by virtue of being acidic. Probably salt water or a baking soda solution would both work too. It's all about making sure those bacteria are dead, and their stinky byproducts are gone. Both baking soda and vinegar will react forcefully with almost anything organic and on average they won't smell as bad as previously. Don't mix baking soda and vinegar. Not dangerous, messy.