Most of us probably fall into the category of a blue collar trader, since we usually have another source of income and just dabble in the financial markets, knowing that we fall far short of what the pros usually can do...or at least talk about doing.
The opposite of a blue collar trader would be a professional trader, who buys and sells investments for a living. A blue collar trader is not sitting around in his or her blue uniform making multi-million dollar trades in large volumes, but rather invests as a hobby, or to earn some extra money. He is not particularly knowledgeable or experienced in trading, and may need to seek the advice of a professional broker. Of course, he's free to do so while wearing, uh...any color shirt.
A blue collar trader might spend more time than the average person deciding which funds their 401(k) or IRA should be invested in; however, they also might buy a stock based not on careful research, but an off-handed remark from a friend, or some news they read online, or that day's astrology chart. Others stick to the tried-and-true blue chip stocks and avoid the riskier investments, such as buying on margins.