Well – What is actual guest tipping behavior for wine?
This behavior applies not only in restaurants but to any wine sales or guest appreciation.
Actually, if you look on the web or in printed material about how much to tip for wine, many experts in the wine business and writers will recommend 15-20% (in the U.S.) on a total food plus wine bill before sales tax (mostly) or including tax (some).
Of course, the experts are biased in favor of big tips!
Is that how guests see it? Apparently not!