Same here. Or worse.... You're changing in the dressing room, and they knock on the door while you have 1 leg in the jeans, 1 leg out.. and they say: "HOWS EVERYTHING IN THERE? NEED A DIFFERENT SIZE? CAN I RUB HONEY ON YOUR THIGHS?"
Ok, the last part isn't true, cause I'd like that, but you get the picture... lol
a healthy smile sprinkled with a bit of gratitude is always nice.
Whenever I buy something and want some help nobody knows anything about things they sell except the info that's written on it. For example when you go to a shop to buy an lcd tv they won't tell you much more than that it's contrast, reaction time and brightness level is great blabla (which is all written on that particular tv). They won't tell you that it's worthless to consider those parameters. They won't tell you about technologies used or why one tv is better than another in an intelligent way (except comparing 2 irrelevant parameters you already see). Same with shopping for any other electonic device or any service. That's why I always do a little research before buying stuff and go shopping after I already know what I want to see/try and then when I go to buy it annoying shopkeepers want to convince me into getting something more shitty. I hate shopkeepers that can't even do their shitty job right. They don't have much to learn about things or services that they're selling. I find the customer service useless.

As far as wanting to be left alone etc. I can agree because I'm not a social person but what do you expect a worker to do? It's better getting treated like you don't exist. And some people want that kind of service.
So, I say again - a healthy smile and a bit of gratitude in my opinion is at the top of the list and that kind of service should a plus to everyone.