Wine Tasting

[BBB]

I was recently in the Alsace trying to expand my knowledge (braking away from South Africa) of wines.

At some of the Domains I had to ask for a small bucket to pour the remaining wine I did not want to finish (swallow). In other Domains a spittoon was present at each table. At these domains it was clear (observing the other patrons) that it was not just common practice to pour the remaining wine out, but not to even swallow the wine.

What is the most common practice for wine tasting and why?