When I am feeling strong, I respond to stupid phrases such as those in the book by taking them both literally and seriously. If the sales assistant says 'Are you alright there?' just say 'I'm sorry? In what sense?' If at the till about to pay you're asked 'How are you?' look puzzled and say 'I'm sorry, I can't remember when we met?' - also usable if addressed by first name. 'Costs are spiralling out of control' - 'Well at least they're coming down!' You get the idea. Control your environment!
I've tried this at the till - after waiting in a queue for a long time, when it was my turn and the assistant turned to me with "Are you alright?" and I replied that I needed to pay, it just resulted in puzzlement for her and embarrassment for me! But I take your point. I was very tempted to ask her what made her think I wasn't 'alright', and whether she meant it in a medical sense, but this would've been even worse. Whatever happened to "Hello"? (Preferably with a smile. But maybe that's too much to ask.)