When you are engaged in the market and looking for short-term gains based on reading the tape, there is a powerful temptation to get in ahead of the crowd. Just as one can jump the gun and buy a stock that is on the cusp of a breakout but doesn't break out and instead turns lower in a hurry, so too can one be victimized by tape readings that are compelling. A stock may see a spike in volume but with no news, and many investors jump into the fray only to be disappointed days later. You have to be very careful of these head fakes.
I have been the victim of so many head fakes I've lost count. I have also been deliberately set up a few times. I don't get as many of the calls as I used to, but in the early 1990s my office was like hot-stock-tip central. This is before the Internet became a major communication force.