I was never a coffee-drinker until Starbucks. I don’t remember how it happened – before I realized it, a cup of “tall decaf mocha” became part of my daily routines.
I secretly doubt they put some additive ingredient into the coffee. To test it out, I went to taste the Italian coffee at Niebaum-Coppola on the University Ave. of Palo Alto, and French coffee at La Baguette in Stanford Shopping Center. Maybe because I am not a professional coffee drinker, although those coffees have some exotic flavor, they are not as addictive as Starbucks’.
One amazing thing about the Starbucks coffee is the consistency of its quality. The Starbucks coffee in Vienna tasted almost exactly the same with the Starbucks coffee in Shanghai. What’s even more amazing is the consistency of its price, regardless of income levels of the different countries. With GDP per capita only $1,100 (compared with GDP per capita $27,000 in the US), the Starbucks in Shanghai are packed with local Shanghaineses along with the expatriates and foreigners.
One thing different, though, is the size. In both Asia and Europe, they 
don’t have size “ventti.” They have “short”, “tall” and “grande”. Sometimes, people say “small”, “medium” and “large”. So, if you are not careful, you may mess up “tall” with “short”. 🙂
Well, I love Starbucks coffee, period. Following the moderation rule, I discipline myself to drink one Starbucks coffee a day.
Thanks, Donnoa-Lee, for the comments. I agree that my body wants those things (even though I try to not eat much sugar).
You obviously aren’t alone in your love for the drinks. But I doubt it is the taste of the coffee itself that you are addicted to. With all of the syrup (sugar) and milk in the drinks along with the caffeine, I am inclined to think that your body wants those things rather than your mouth/brain wanting a great cup of coffee.
Indeed, their marketing and consistency is responsible for their worldwide success.