I really don't care what my signature looks like. I can't even remember the last time I signed for something, and I'm not bothered about what the UPS guy thinks of my signature. Maybe I'm missing some cultural difference here, but I've never judged anyone on their signature, nor do I expect to be judged by my own.
As for Graphology being a science? It isn't. I realize that saying so supports your marketing copy, but the style of someone's handwriting is purely a product of the method by which they were taught to write.