For certain experiments, I think placebo controlled trials are beneficial in helping researchers investigate the affects of a drug. Placebos are usually used in comparison to the experimental drug and act as a control. Say for example there is this new drug that can alleviate the effects of a migraine. An ideal study would be to have subjects either take the experimental drug or a placebo (most likely a sugar- pill) after an onset of a migraine. The researcher/investigator can then look at the observations made by the subjects and compare the affects of the placebo and experimental drug. Because the placebo acts as a control, there should be no relieved symptoms after using this pill, making it ideal for a comparison.