@AmySue's baby was a preemie, though, so I can see wanting to be extra cautious.
Here is when I have pumped & dumped -- if DH & I have gone out on a date or to a party & MIL watched the baby and she just had a bottle. I'd pump when I got home to maintain my supply and avoid enorgement, but I didn't really want alcohol-content milk in the fridge/freezer, even if I'd have nursed in the same situation, you know?
I'm 100% comfortable nursing after 1 glass of wine/beer.
This is from Dr. Jack Newman:
A mother should not drink alcohol while breastfeeding. Not true! Reasonable alcohol intake should not be discouraged at all. As is the case with most drugs, very little alcohol comes out in the milk. The mother can take some alcohol and continue breastfeeding as she normally does. Prohibiting alcohol is another way we make life unnecessarily restrictive for breastfeeding mothers.