Soldato
Problem is that once you start making espresso at home you start picking out the errors in starbucks etc.. Like the bad coffee, the foam etc, etc.. Mind you the Costa coffee in Waterstones in Reading (as you exit the Oracle) is pretty good and the espresso was drinkable!
They tend to over-roast (or burn) the beans in Starbucks et al, this way they can get a consistent taste™ when they buy different beans and blends etc.