One aspect of my job as criminal defense attorney is answering questions about the longterm impacts of criminal convictions. It's not easy. Over the years, I have talked to enough Human Resources (HR) personnel of various employers [often the parents of my clients] to learn that job applicants who have one or more criminal convictions are treated much worse in the hiring process than those with "spotless" records. Depending on the employer, and certainly depending on the kind of work (e.g., public safety, financial, and education) any criminal conviction (even the most innocuous of misdemeanors (e.g., "disturbing the peace")) might destroy one's chances of getting hired. It is often a heavily weighted factor that might cause someone to be pushed downward in the ranks of qualified applicants.
One 2006 study called The Impact of Youth Criminal Behavior on Adult Earnings found that, "[h]aving been either charged with or convicted of a crime decreases earnings by about 10 percent early in a young adult’s working career. However, receiving a conviction when young lowers subsequent adult earnings by about 13%." The study took into account that there are demographic variables that are correlated with both lower earnings and criminality. This was dealt with by comparing the earnings of siblings who didn't have convictions as youths with their siblings who did. Notably, the study was based upon data gathered for more than a ten year period unlike many other studies of its kind.
Adding to this concern is my intuitive sense that the current population explosion, globalization of the economy, and the increasing proliferation and accessibility of criminal conviction data brought by the digitial age are all factors which will increase the negative impact of a criminal past on one's earning potential.
It is difficult, at times, to impress upon people who are not versed in this subject matter to take their criminal charges seriously, and to do what they can to keep their records spotless. Unfortunately, I've talked to (and represented) enough people years down the line who wish they had fought their case now that they know what was truly at stake; their financial well-being. I always encourage these people to pursue any expungement, or related remedy, available to them. However, there is no substitute for avoiding the conviction in the first place.