Dishonest CEOs

Whenever I attend an investor seminar where the CEO of a company is presenting, you would think you would be a fool not to buy it.  In a bull market, most stocks are rising so even the cleaner or taxi driver can give you the 'correct' tip.  After attending to so many seminars, you learn to recognize which CEO is not telling the truth.  Unfortunately, hind sight occurs after a loss.  But what is deceiving is a lying CEO which is no better than a used car salesman.

Many don't tell you about the debt level and level of cash at hand.
Many investors don't realize that no forthcoming production means no profit even with world class deposits uncovered.
Many don't acknowledge that potential find often end up in nothing even when there is oil seeping out of the ground or a naturally occurring oil slick is present.
Many won't reveal the obstacles especially when dealing with developing nations or the greenies.

You also need a geologist degree to understand what the drilling results mean. 

Finally, you want to listen to negative sentiment/statement.  Once I invested in a uranium exploring company.  Someone said that none will be produced because that Flinders Range site is too beautiful...  Luckily I dumped it early but not at its peak.  Subsequent to my selling, the management was unprincipled too; they simply dumped at the site and was fined.