My pleasure. I regretfully have a lot of experience with the topic.
But no, Harls isn't a role model. Oh my gods no, she's a psychotic killer. But I don't think her popularity stems from being a role model, at least not the in the same way you could say of Superman or Captain America. Harley isn't a role model in that she's a quality person, but she does represent freedom for a lot of people who have none.
I think it's more about over coming adversity than anything. I've met a few people (not a lot, but a few) who adore Roy Harper. They don't really care for Spider-Man or Flash, but Roy and his struggle with addiction is something they can relate to. Roy reflects their own lives in a way other characters don't and that's the appeal for them.