I have been flying for only about 200 hours and I have gained the reputation, where I fly, of being almost crazy when it comes to pre-flight. On about 50% of my preflights, I usually find something not right. Most of the time they are not major, usually just a loose screw somewhere, but I have found conections on the control surfaces whos' screws were about 1 thread from falling off, I have found water, and lots of it, in the fuel many times, I have found both major and minor oil leaks (this has been one of my pet-pieves, checking oil, since on my second solo, I lost all oil shortly after take-off because an oil gasket disentigrated), and on retractable gear aircraft, I have found screws on the landing gear plate backed out. There have been many other problems I have found all because I insist on a thourough pre-flight. After all these problems, I have gotten into the habit, and hope to stay in the habit of a good pre-flight.
I have also seen the pilots who get in the plane without a pre-flight and take off without a run up and I just hope that if something goes wrong, they don't take anyone with them.
Seanpcola, I agree with you about the ultralights. I believe that they are a great thing for people willing to learn how to properly and safely fly them but unfortunately, I have seen many accidents and lost someone close because they did not respect thier flying machines. After my friend learned how to spin in an ultralight, he took his son up with him and entered a spin at a low altitude. The ultralight crashed and I was told it caught fire and burned both him and his son to death while his wife and daughter watched (they couldn't get to them in time). I have known many ultralight pilots who go through the process of thouroughly learning about aerodynamics and how to properly care for ultralights and are great pilots, but I have known many who don't even get instruction, just hop in and fly.