Don't Question the Drunk

I'm not sure the author of this story but:

I was shopping at the local supermarket where I selected:
A 2 litre bottle of skim milk
A carton of eggs
A litre of orange juice
A head of lettuce
A 700g jar of coffee
A 1kg of bacon

As I was unloading my items on the conveyor belt to check out, a drunk standing behind me watched as I placed the items in front of thecashier. While the cashier was ringing up the purchases, the drunk calmly stated,"You must be single." I was a bit startled by this proclamation, but I was intrigued by the derelict's intuition, since I was indeed single.
I looked at the six items on the belt and saw nothing particularly unusual about my selections that could have tipped off the drunk to my marital status. Curiosity getting the better of me, I said: "Well, you know what, you're absolutely right. But how on earth did you know that?"
The drunk replied, "Cause you're ugly."