I have to say I'm usually happy to receive feedback both positive and negative from my customers, as it gives me the opportunity, where possible, to exceed their expectations - of course, this can only happen if the offending article is drawn to your attention at the time, its not much good if someone's at the till, ready to pay, and they're saying to you, "By the way, you're coffee is rubbish!" Sometimes its the difference between changing dates on the beans that you're using, and still dialling in the grind (although in theory this ought to be a straight forward adjustment, but in reality this is not always the case), or you're in the process of still training a new person up on the coffee machine, who brings with them practises from elsewhere, which may not be suited to the beans that you're using, the equipment that you're working on, or you're stated preferences for making coffee I was in New Zealand recently for a family gathering, and managed to tiki tour around a bit, trying coffees from all over the North Island (although, not as much as I would've liked as the main reason for the trip was a family reunion), and I had some excellent and exceptional coffees (a few but not much), some really good coffees almost everywhere I went (which was mostly the case), and a couple of rubbish ones which I just couldnt drink (maybe two or three) In the case of the rubbish ones I didnt bother saying anything, I just paid my money and left. I figured that it actually takes quite a lot of effort to make a rubbish coffee (as it does a good one), and if the barista in question was trying so hard to make terrible coffee (intentional or otherwise), then I didnt really have the time, patience, or temperament, to tell them otherwise In the case of the mostly good coffees, I was surprised by how many otherwise good coffee extractions were let down by poor milk (most places I tried use Anchor milk, and I'm not sure how its processed but it just tastes ultra-pasturised to me, either that or the milk in question had been reheated), which just didnt sit well with me And in the truly exceptional cases (some of which were out of the way / off the beaten track, and quite unexpected!), I went out of my way to inform the staff how much I enjoyed their coffee! At the end of the day a lot of effort at every step along the production line goes into making a quality coffee, and it only takes one mishap along the way to send it all pear shaped, whether it be bean selection, roast profile, choice of milk, experience of the barista, machine maintenance, grind selection etc, and so on... The way I figure it is that its the responsibility of the cafe proprietor to quality control check as many variables as possible along the way, which of course is not always possible, and sometimes we get it wrong, but there are safety checks that happen along the way, along with staff development, palate knowledge and structure, and asking the customer what they want and endeavouring to provide it, which help to eliminate some of the variables along the way Do I feel that its my job to tell a cafe what they're doing wrong? In most instances, not. But if it seems obvious to me that the coffee I'm drinking is a slight aberration on what I ordered, or what I would consider to be the industry 'norm,' i will most certainly take it up with the establishment in question Having said that I just dont like 'green' or overly fruity / high acid espresso based coffees, at least not with milk, and will generally avoid places that preference this kind coffee my five cents worth after two double espressos! ACg