It's got nothing to do with flavor or anything like that. The reason people suggested whiskey and vodka is that they're both distilled spirits, IOW high-alcohol, IOW sanitary liquids that will not harbor bacteria growth. The reason people put this in their airlocks is in case the airlock liquid gets sucked into the beer (usually when there's a large temp drop inside). Alternately, you can use star-san solution, et al, but the problem I've noticed with StarSan is that, because it's a foaming agent, vigorous airlock activity during primary fermentation causes the airlock liquid to foam up and possibly deplete to below the level of the airlock insert.