I don't think she's particularly clever, she just knew to surround herself with people who had learning difficulties or vulnerabilities that gave her the upper hand intellectually.
It's interesting that the first husband (who essentially 'won') didn't seem to have any of the vulnerabilities that the other men did.
It was obvious she was faking the medical issues pretty quickly. The difference in her the minute she found out she was being arrested, even the way she spoke changed!
I do hope her children are able to live their lives without damage from her. Sadly, I've read enough threads from adult children of narcissists on here (and my own father is the child of a parent with a personality disorder) to think that they may not come away completely unscathed.