The happy go lucky thing is a bit interesting.
I work with someone who is always very upbeat and positive. It's just her natural state, because she likes to be happy. Personally, I love to work with her, she's a riot. But there are a lot of people that can't stand working with her. They always say things along the lines of she's had at her job or she's got attitude or they'll just outright mock her. She's actually really good at her job, especially with the customers. And the only time she gives any real 'tude is if that's how someone treats her first and repeatedly.
She's an honest and happy person, which makes her an outcast. She doesn't fit into the normal, miserable, thing most of the people working there got going on, so they essentially attack that irregularity.
Misery loves company, after all