In the case of people like the friend I described, the effect can sometimes be very subtle and not noticeable at first. Certainly when you look at my post it all looks like a bad movie, but remember we all discovered it over a period of months and years. When M. first came on the scene, we were bowled over by her charm in the beginning and it wasn't until later that we started realizing how unlikely it was that so many things could happen to one person--and if she'd had the glorious life she'd claimed, it had left very few traces on her present. With most people, you can see continuity with their pasts; I believe my bf when he says he raced sled dogs, for instance, because he has photos and clippings, and the stories he tells are consistent with what I know of his personality and his past. With M., there was a discontinuity; she seemed to reinvent herself every few years, once you put the pieces of the pattern together.
On a less spectacular level, I had a friend in high school who would tell me about the most amazing experiences she'd had, yet they always seemed to happen when I wasn't around, and when she was with other people I was not friendly with. One of the more amusing claims was that she'd gone to California (alone) for a week to stay with a family friend, and her dark hair had gone reddish-blonde in the meantime. She could produce no souvenirs or photos of this visit, and knowing her parents there was no way they'd just put her on a plane; if she went at all, they'd go with her, and they hadn't. I wondered for ages why she would bother making up all this crap, but her self-image was heavily invested in thinking of herself as the cool one, the sexy and irresistibly attractive one, and because her father was a doctor she felt herself to be socially above everyone else anyway. Thus, she needed US to believe that her parents would blithely ship her off to California alone for a sun&surf vacation, while she stayed at home in the meantime (they lived in a very rural area, so no chance of running into her on the street) and experimented with hair dyes. I had often seen her involve her mother in lies and I have no doubt that if I had said something in front of her, her mother would back her up. Her father OTOH would have laughed at her and told her off for telling stories, which was why the girl was so adamant that we not mention it in front of him.
On a less spectacular level, I had a friend in high school who would tell me about the most amazing experiences she'd had, yet they always seemed to happen when I wasn't around, and when she was with other people I was not friendly with. One of the more amusing claims was that she'd gone to California (alone) for a week to stay with a family friend, and her dark hair had gone reddish-blonde in the meantime. She could produce no souvenirs or photos of this visit, and knowing her parents there was no way they'd just put her on a plane; if she went at all, they'd go with her, and they hadn't. I wondered for ages why she would bother making up all this crap, but her self-image was heavily invested in thinking of herself as the cool one, the sexy and irresistibly attractive one, and because her father was a doctor she felt herself to be socially above everyone else anyway. Thus, she needed US to believe that her parents would blithely ship her off to California alone for a sun&surf vacation, while she stayed at home in the meantime (they lived in a very rural area, so no chance of running into her on the street) and experimented with hair dyes. I had often seen her involve her mother in lies and I have no doubt that if I had said something in front of her, her mother would back her up. Her father OTOH would have laughed at her and told her off for telling stories, which was why the girl was so adamant that we not mention it in front of him.