Not long after recently arriving in San Francisco, I bought a large capuccino to go at a Starbucks store near the Hyde St wharf. The 'service' was unfriendly and surly. When the coffee arrived, I was astonished at its lightness. It ended up having two sips' worth of coffee hiding under the froth.
The only fortunate thing about this event was that it was at the beginning of my American trip. I was therefore able to avoid buying coffee at any other Starbucks outlets during the ensuing month that I was in the USA. I therefore directed my custom (1-2 coffees per day) to other coffee providers. I found a smaller but much nicer chain in San Francisco.
Fortunately, it is difficult to get a bad coffee in my home town (Perth, Western Australia), other than perhaps at the few Starbucks outlets that seem to have popped up lately (which I won't ever be patronising).