I love optical illusions. It is fascinating how our minds can be tricked. The good folks at grand-illusions have a dragon illusion that you can download and build yourself. Here is a video showing the illusion in more detail.
This seems to be another example of the brain assigning a symbol to something (see earlier post) to make processing lots of information quicker. In this case, it seems the brain "knows" that if a dragon is looking at us that its nose would be closer to us than its eyes. It is called the "Hollow Face Illusion".
Just as our brain can interpret what we see as two completely different views, it appears it does the same thing with people. For example, let's say you are looking at a playground and you see a child climbing up a slide. You also see an adult in the shadows hiding behind a nearby tree peeking out and watching the child.
If you don't know this adult chances are you will remember being taught "stranger danger!" and you will immediately become suspicious that this might be a predator. However, if you knew this adult you would assume that they are playing hide-and-seek. Two completely different conclusions from the same situation. Obviously, previous experience colors our perception.
Inevitably you, or someone in your company, will make a mistake. At that point your customer's view of you will determine the conclusion they draw. If you are a stranger they may view the mistake as a callous disregard for customers from a company that only cares about its profits. However, if they have had several good experiences with your company they will be more likely to give you the benefit of the doubt.
If your customers only hear from you when you are selling something you are missing out on a chance to build trust and change from being a stranger to a friend. Why not send a non-salesy greeting to them on their birthday, let them get to know you, it is good insurance for future mishaps and it is what friends do.