AH, but the end of an affair is tough.

The reproaches, the recriminations, the shock of your ex-beloved harsh in daylight without the sooth of oxytocin mist. Discovering a scoundrel unworthy of your affections: a waster, a rogue, a tax avoider.

Starbucks, you big beast, what a fall from favour. After 14 years of trading in the UK the company has made the worst of faux pas by, like other large corporations, paying minimum tax. For weeks the lackadaisical tax attitudes have been rattling round the press, the latest this week being Kris Engskov, UK managing director, having a strop at David Cameron, who he believes singled out Starbucks for criticism.

Eight years I worked in Starbucks. It was different then. We had the staff. We were young and energetic and waggish. The boys had girlfriends with intimidating hair. They rode about on skateboards and did graffiti in their spare time. We wore chinos hanging low on the hips and white shirts with the sleeves rolled elbow high. We were preppy with an edge and we cared about the coffee, we really did.

At that time America was crisp and fabulous, Friends was in vogue, Ben and Jerry's and Hershey's were gourmet foods available in speciality stores. The shop was full of slim teenagers wanting flavoured steamed milk, twentysomethings with library books, a stream of office workers and tourists, Californians in search of a tall, wet "lah-day" made with 2%, steamed to 163 degrees centigrade precisely. The American tourists sniffed us out: we spoke their language. Left to get on with things, stores flourished. They had character.

Then the Seattle bosses opted for growth. From three quirky stores in Glasgow a dozen flourished, more like aspergillus than aster. We joked a new branch would open in our customer loos. Cluster bombing, I believe it was called. As long as a larger store turned a profit smaller stores could kill off the competition, regardless of making a loss.

To control such a sprawling organisation – 650 stores in the UK alone – takes a determined fist in an iron glove. We were told to create romance and theatre. We were told to "go the extra mile", cultivate a "just say yes" policy, "that'll do won't do". Once Howard Shultz, the Steve Jobs of Starbucks, left a message on the internal voicemail after partners in New York tried to unionise. They'd let down the Starbucks family. We were given lines to parrot, words were banned, waste sandwiches were to be unwrapped at the end of the evening before being binned so homeless people didn't salvage them.

Meanwhile the company tootled on about corporate social responsibility, that old oxymoron. The coffee was not Fair Trade but "fairly traded". Oxfam worked with us. At that point the yummy mummies moved in. Customers moaned constantly that the cups were too big, the coffee too weak, the milk too cold.

Lately these promotions, the £1.50 latte on a Monday morning, seem a bit desperate. They seem a bit jewellery when flowers would have done.

After the promises we fell in love and after love the disenchantment set in. Now we've confirmed they've been cheating on us all along. And we want revenge. Revenge, and a decent cup of coffee.