If it's a screening for a DOT physical and you drank the night before, you just might be kissing your job away also, as they are checking for booze also.
Understandable, but this is for a sales job. Maybe it is a position that requires driving a company car or something, could be just answering the phone. I have had to pick up the slack for a lot of hungover co-workers before. And having worked with a guy that used to keep 2 ounces of dope in his freezer, who was never late to work and was ready to go at 7:30 every morning, I have a different idea about it.