I used some wet watercolor paint for this test to see how alcohol would work as a painting medium. The wet watercolor and pure alcohol are the far left streaks of each color. The next stripe to the right is watercolor and pure water, and the smaller stripe (an afterthought, so I didn't leave enough room to properly experiment) is a combination of alcohol and water.
I finally realize that watercolor paint isn't made to be used with straight alcohol. It doesn't like it at all, but that's what makes the effect of adding drops of alcohol to watery watercolor interesting--the watercolor practically runs away from the alcohol.
Just because they weren't made to be used together doesn't mean the effect isn't interesting. Although I'm sure some watercolor purists would probably disagree, it could have some applications in future paintings where a gritty texture is in order.