I've personally found the staff to be fine whenever I've visited the shop since its relocation, I've noticed that if you smile and speak to them politely and with respect they treat me in kind, if I was grumpy and dour-faced (I'm not saying any of you are) I'd expect a similar response.
Whilst it is expected that customer service staff should appear happy, jovial and helpful all of the time at the end of the day lets not forget that they are people, and as such are prone to off-days - it is a low paid profession in which they have to deal with long periods of inactivity coupled with dealing with a percentage of customers who are often dismissive of them and occasionally downright rude. I'm sure that description rings bells with many of you in your respective employment, and can you honestly say you are happy, smiley and cheerful in work all day?