"Rat Fink... fiddles with a beaker that's smoking and bubbling as per the Mad Scientist Lab Rulebook." -Ed Harris, Agony BoothSince Ed didn't provide a link, I think we should make our own rule book, both for Hollywood and woo stereotypes.
1. All scientists work with weirdly shaped bottles and flasks of colorful chemicals. These chemicals are always bubbling or smoking. It doesn't matter what kind of scientist he is. Colorful chemicals equals credibility.
2. If your introductory scene doesn't involve you carefully pouring something into a test tube, you're not a scientist.
3. A scientist's talent is directly proportional to the thickness of his German accent. The same is true of his madness.
4. Science is subject to the Storm Trooper Effect. A lone scientist working in a remote place is much more likely to produce earth-shattering breakthroughs than countless scientists and lab assistants working in a prestigious university in the center of a metropolis.
5. Atheist scientists are soulless ultra-materialists who reject the existence and importance of emotion. Religious scientists always make breakthroughs that involve, or at least hint at, the supernatural and are ridiculed and never believed until the climax.
6. There's usually someone who steals the scientist's secret/inventor's prototype for use in the eeeee-ville military. If the scientist/inventor explicitly expresses anti-military views, the probability jumps to 100%.
6a. If the scientist has a daughter, she will be kidnapped for use as a bargaining chip to acquire the secret or force the scientist to work for the kidnappers.
7. Scientists never believe that their new inventions can cause environmental problems or cause side effects.
7a. If they are convinced, they probably already knew and just don't care.
8. If magic exists in the movie, science and technology are always evil. Magic is always environmentally friendly, and all nature scenes are nice and pretty. Swamps and wastelands are always the scientists' fault.
8a. When used against the giant monster, technological weapons built by optimistic scientists always fail where the magic sword of legend will succeed.
9. Scientists are always socially inept, absent-minded, and unable to party.
10. Magic tends to show up only after science bombs everything back into the stone age.
Okay, that should be enough to get you started.