As a voice major & voice instructor, I was taught (& told by Dr.'s that alcohol is VERY damaging to one's vocal folds (aka vocal chords). A sore throat is often caused by either overuse/mususe or germs/viruses & such. If one is cautious, one will keep voice use to minimun, practice frequent hand washing (Dr's say the #1 thing to prevent the spread of germs!), and wear a scarf in the winter, & stay away from allergins & strong chemicals all the time. Just before & during gigs: DO NOT use alcohol nor drink very hot or very cold beverages. Room temperature water is best. If one has lots of allergies, antihistimines & decongrstants can dry out the throat, also. One should also seek out proper voice training/coaching, and learn to vocalize properly before performances so as to have the voice warmed up & so that you cause no excess strain on your vocal folds.