You wrote, "Is it possible that acetaldehyde and ethanol behave differently from lactic acid? Maybe." I'll note that they behave differently in one way: acetaldehyde has a very low boiling point, 68.36°F. That's why you can smell it so strongly on an alcoholic's breath! There's an argument that low levels of acetaldehyde produced in the mouth will evaporate into the breath quickly and constantly, while lactic acid sticks around. However, the speed at which it will evaporate is an empirical question, and I'm not confident in saying there will be ... (read more)
Interesting.
You wrote, "Is it possible that acetaldehyde and ethanol behave differently from lactic acid? Maybe."
I'll note that they behave differently in one way: acetaldehyde has a very low boiling point, 68.36°F. That's why you can smell it so strongly on an alcoholic's breath! There's an argument that low levels of acetaldehyde produced in the mouth will evaporate into the breath quickly and constantly, while lactic acid sticks around. However, the speed at which it will evaporate is an empirical question, and I'm not confident in saying there will be ... (read more)