Depends on the drug. Mushrooms are fantastic for bringing certain parts of your personality to your attention without the cloud of the ego. You can truly view yourself through unbiased eyes and see your deepest flaws. A lot of bad trips result from people discovering things about themselves that they weren't ready to learn. I'm smoking weed right now. Weed's pretty good for seeing through bullshit, but you're not going to learn any real personal truths from it.