Lunch with Sharon

Had lunch with some friends today, including Sharon.  I'm sort of on the fence about Sharon.  There's something about her that seems really nervous.  And she seems to struggle to understand what I'm saying.  I'm not sure if this is an issue of me or her, although mostly everyone else gets me. 
Sharon was talking about her brother, who she calls "retarded."  (I could hear Dan's disapproval ringing through my ears as she said that.)  She mentioned that her brother lives alone, but loves movies.  I mentioned maybe as a present she'd get him Netflix, since you only have to pay a monthly fee.  I think she misunderstood me, and thought that you had to pay for each individual movie.  I tried to explain that no, you just pay the fee and get as few or many movies as you want. 
There's something rather nervous about her.  She speaks fast, not to the point that I can't understand her, just in a way that makes me wonder if she feels she has to impress me. 
She told me that, unlike a lot of other girls my age, I'm actually interesting and smart.  It was a nice compliment, but I wonder if it makes her feel like she has to live up to some imaginary standard. 
Lately, several people have told me that I scare them or make them feel like they aren't measuring up, which I feel terrible about, because I generally don't intend to make anyone feel that way.  Occasionally, someone will tick me off and I will "pull rank" as it were, and lean on them slightly so they know I don't approve.  But if I keep someone around, generally that's because I like them.