By Dan Weil To deal with a problematic co-worker, you have to be able to identify them first. Sometimes that involves a sniff test. Do you think some of your co-workers are real jerks? You may have good reason to feel that way, but they may also think the same about you. While 93% of U.S. employees say they like their colleagues in general, 80% say they have at least one terrible co-worker, according to a survey by ResumeLab, an online resume advice site. Some of us seem to work with quite a few nimrods. Among those of us suffering from this plight, 50% have three to four terrible workers, 34%…