I don't believe that people really change. They may spruce up their outward appearance, filter their words, and mask their malicious intentions, but they never really change. I believe in evolution, though. I evolve every day. With new experiences, I gain new understandings. And if I'm of a mood, I am actually capable of learning from past mistakes, failures and triumphs.
One day I will champion an alternate cause because I'm a sucker for an under-dog, or I love playing Devil's advocate. The next day I will champion the opposite position just to keep my nearest and dearest on their toes. Really, I just enjoy a good argument.
So- beware of anyone who comes to you telling you how much they have changed. It might take some time, but you'll figure it out the hard way. Either they were lying to you before, or they are lying to you now. And that's my helpful life survival tip of the day. You're welcome!