Buying Alcohol - Scruffy vs. Clean-shaven

Is a man less likely to be carded when buying alcohol if he is sporting a scruffy look as opposed to being clean-shaven?

I purchased alcohol 43 times over the past 3 years (January 1, 2011 - December 31, 2014); 19 times with a clean-shaven face, 24 times with stubble on my face.

# of times I was carded over the past three years while my face was clean-shaven: 17
# of times I was carded over the past three years with stubble on my face: 3

Conclusion: 12.5% chance of getting carded with stubble, 89.4% chance of getting carded while clean-shaven.

There certainly could have been other variables that would have influenced the experiment such as my hair length and whether or not I was wearing a coat/hat, whether or not I was with someone, etc. However, I made a note to do a fairly good job of controlling this and would purchase alcohol at different stores at similar times of the day.

I live in Missouri, which allows for alcohol to be purchased in gas stations. Often times, I would simply buy a six-pack of beer while I was conducting my Gas Mileage tests and record whether or not the gas station attendant who sold me the beer carded me.

The results will probably not translate perfectly to every man out there in his twenties. However, there seems to be a clear advantage to having stubble on one's face when buying alcohol.