Ok let me give my two cents.
What annoys me is when an MA doesn't go out of his/her way to help you out or to let you know what's up. It is obvious to the client when they are doing something "half-assed" (without wanting to)
For example: I had saved up A LOT of empties one time and went to the MAC store to redeem them for make-up. I had 14 empties, I took all 14 because I couldn't remember if it was 6 or 7 empties to get a free product. So, this MA got my empties counted them and put them away to the recycling bin they have there.. She came back and told me I was eligible to get 2 things for free.. So I was like, oh it's 7 empties then, she was like no, it's 6. So umm... where are my 2 extra's?? Yeah, so I told her I wanted my two extra and she did a face like she got bothered. I didn't care, she went back to get my extra 2 empties.. No, she did not miscount how many I had, she just didn't want to help me out.
Maybe it is just her personality. I know that if it were me, I would have never done that, would have been like Oh you have 2 extra.. People who work retail(not just MA's) in general need to remember customer service!
Also, one small important detail.... SMILE! By greeting a customer with a smile, than just a plain ol' "Can I help you" or "Are you doing ok?"
See, that MA who didn't give me my extra empties, I had a bad vibe from her from the beginning because she doesn't look friendly or smiles (she's beautiful tho) but still, it's important to set up a way to approac a customer to do a succesfull sale. This way the customer knows who to look for when he/she comes back.
When I go back to the same store, I always tell her NO when she asks me if I need help.