I have used them and I thought that they worked fine. You use them just like you would dip a dip pregnancy test into urine. It's just you dipping into milk. I thought it was fairly accurate as well. I personally never drank and fed my milk to my baby. If I drink, I would just use my freezer stash, but I found this very helpful.
They’re very reliable because they’re very sensitive. So if you have perfume around the strips it will turn blue
You'll be fine to have a few drinks. I have a glass of wine or two or a beer once or twice a week. I try to time my pumping when I start drinking or closer to 2-3 hours after a drink. I exclusively pump. If you pump or nurse while *you start* your drink, the alcohol hasn't been metabolized yet and if you wait long enough it'll be out of your system or in a much lower quantity than say an hour after drinking. I don't bother testing my milk. Are you pumping to feed the milk later? If so and you're concerned, you can mix that milk with another time or day to dilute it.