Hello and welcome!!!!
I'm wondering if the seller suspected mealybugs or something. That would be the only reason to use alcohol that I know of. As Sarah said, for making the leaves clean or shiny it would be lemon or lime juice on them. Check them close to make sure there isn't something lurking. Don't worry about it one way or the other, it's fixable.
You'll enjoy growing orchids. It is so rewarding to see them come into bloom; to perform for you.
If you have time, please post pictures of your new orchids. We all love pictures. We will help you all we can. Again, welcome!