Cos. walk a tricky line with endorsements

NEW YORK -- Nike forgave Tiger Woods after his infidelity was exposed. It welcomed back Michael Vick once he served time for illegal dog-fighting. But the company dropped Lance Armstrong.

The sneaker maker has stood by athletes through several scandals, but this week it became the first company to sever ties with Armstrong in the wake of allegations that he used illegal drugs to boost his performance over his 20-plus year racing career.

At least five other companies followed Nike's lead, highlighting the tricky relationship that evolves when marketers sign multimillion-dollar deals for celebrity and athletes to endorse their products. When something goes wrong, companies act as the judge and jury when deciding whether to continue those deals.