There is no way to determine how long alcohol remains detectable on the breath. Smelling the breath is not a reliable indicator of the level of alcohol in the system, according to law enforcement findings.
Detecting alcohol on the breath is difficult to do, because most alcohol does not have a distinct odor. After consuming any type of alcoholic drink, the alcohol enters the bloodstream. The only reliable way to determine the level of alcohol in the system is through a Breathalyzer test.
Blood alcohol content is a concern for law enforcement when a person has too many drinks and decides to drive. There is no way to defeat the readings of a BAC test if pulled over by police on suspicion of drinking and driving.