I apologize if this isn't news and the topic has been beaten to death; I couldn't find it when i did a search (checked both bay area board and Chowhound generally)
I was in Yountville last weekend, stopped by Bouchon for coffee & pastry. The pastries were good, not spectacular. The regular coffee, i.e. "here's a cup, go pump yourself a cup of coffee from the back bar" -- was OK, nothing remarkable in either direction good or bad.
I made the mistake of ordering a latte instead of a second cup of coffee: I was STUNNED at just how BAD that latte was. I recall noticing when they made it, they stuck some kind of teabag thing into the espresso machine in place of tamped-down fresh-ground espresso -- that must've been the root cause, since I'm pretty sure the milk hadn't gone sour (it was Clover, maybe organic).
Perhaps I've been spoiled by Blue Bottle, but that mess tasted like it spewed out of my company's Kafeteria Koffee Maker at 5:30 pm, after 'baking' on the burner since 7 am.
I took one sip, flinched, took a second to make sure it was really as bad as I thought (i thought Thomas Keller was famed for attention to detail?), then I tossed it straight in the trash. If it's pastries & latte you're after, get at least the latte part ELSEWHERE!