Sometimes a mistake can wind up looking better than what you planned. I bought a calla lily to paint and then never got around to painting it. It looked lost and forlorn and then started to die. Rather than throw it away, I decided to take a photo of it. Pulling out my incredibly old digital camera that my friend Hal gave me, I took a shot only to discover the flash hadn't gone off. But I really like the way the picture came out. Very faded and grainy. It looked somehow older and more atmospheric that if the flash had gone off. I think sometimes things you don't plan work out better than the planned action - there's a spontaneity that you miss if you are too exact.
My former Watercolor instructor, William Kolbe, often based his paintings on accidents (though he really didn't say they were). He called them treatments or experiments. He'd lay some color down in a wash and cover it with plastic or wax paper and then develop the paintings from that. It made the painting more alive in many ways. I still do that when I paint. It does make the backgrounds more interesting. Terri, my printmaking instructor often says that in printmaking you accept the flaws on the plates or the chip in woodblock, because it adds character and depth. I think that's probably true in real life as well. It's how you respond to the accident and incorporate it is how well you do in life.
My grandmother was a believer in unplanned activities or accidents. She'd get in her car and just drive, finding something of value every time she looked. Going along a familiar path, she'd take a left turn instead of a right one and find a wonderfully charming house or a cemetery that someone she knew was buried in and had forgotten about. She'd make a normal drive to the post office an adventure and I loved going with her but her daughters fretted especially when she was older and her driving had deteriorated. I to think that I am similar to her in this. Certainly I've had a great deal of 'accidents' that turn out better because I accepted them in a spirit of adventure.