Badly poured Guinness. It's expensive yet almost invariably bar staff can't make a decent effort of producing a nice pint that's not half foamy ice cream. Morons who can't be bothered to get better at thier job.
The phrase 'bear with me'. Arrrrgh. Grrrr! Run! A bear! It's customer service (pah!) talk that's supposed to mean 'one moment please' but instead means having to grit your teeth while yet another inept idiot,who isn't capable of performing thier work efficiently, has to go away or put you on hold in order to ask a superior how to do something they should know already. My wife and I had lunch in town last weekend, I heard 'bear with me' dozens of times. Quit it.
Lastly, a seemingly small matter, but one that bugs the living hell out of me. I pay in cash for everything I can, yet cash handling skills are evaporating. When I recieve my change, 9 times out of 10 the order I get my transaction back into my hand is - receipt, note(s), coins. The result is an unweildy parcel that requires me to put my purchase down to untangle and try not to spill the whole lot onto the floor. It's because people can't do basic mental arithmatic, so look at the till and pick the big numbers first, making it easier for them to handle in one go, but very awkward for the customer. On the nowadays rare occasion that a smart shopkeeper places into my hand (and counts as they go), first the coins, then the notes and finally offer a receipt, it is a little courtesy that makes me rejoice.
Hmm, I think what grinds my gears is bollocks service when I'm paying for something. Aah, feel a bit better for getting that off my chest!