PRECONDITIONING

Does this dog look scary to you?  The first time I saw her, she looked scary to me.  I guess that I was concerned that she would fight with my dogs.  Many other people, upon first seeing her have expressed the same feelings to me.  Apparently, we have some preconceived ideas.  I don't know where they come from exactly.
She lives at a transmission repair place next to the field by the church where I walk the dogs.  She spends most of her days laying in the field.  Her owner used to yell harshly at her whenever she came over toward us.  But not anymore.  I think she is afraid of her own shadow.  We have been doing this for some years now, and she only recently has been able to be within ten feet of me.  She likes to smell around with the other dogs, but if I quietly say hello to her, she slinks away toward home.  Now in the last week, she will stand 3 to 4 feet from me, and I can speak to her, but not move toward her.  I cannot make myself view her as scary anymore.  
I am most amazed by what it is that at first sight makes her look scary to people.  And how wrong that idea is.  How possibly right could we be about our judgments of people at first sight?