I am a “celebrity” — broadly speaking — spokesperson for a company I always loved. I shop there, enjoy its aesthetic and admire its charitable giving. But I’ve learned that its labor practices here and abroad are not so admirable, and I’m ashamed I took the job. May I use my Web site to promote organizations that oppose such practices — anti-sweatshop groups, for example? Would donating some of my spokesperson money to charity offset any harm I do? And most important, may I keep this job? NAME WITHHELD, CALIFORNIA

You should not act in ways that make you feel “ashamed” — a powerful word — and so you should not keep this job. A nagging conscience is, well, a big nag, and worth heeding. But it is not an entirely reliable nag, not an infallible gauge of morality. Nero fiddled cheerfully while Rome burned; my imaginary Uncle Milt is awash in guilt if he moves beyond the missionary position. Before heeding even my nagging, there are other factors to consider.

We should strive to live our values, but if we demanded perfection from our employers, none of us could work at all. Years ago I was a staff writer for David Letterman, when his show was on NBC, which was then acquired by G.E., major weapons maker, big-time polluter of the Hudson — from my perspective, bad guys. But I did not feel compelled to quit my job, which was peripheral to those activities I disdained. (And really fun. And well paid. Moral reasoning or self-justification? It can be tough to distinguish.)

Your position is more precarious because you actively promote a company that violates your principles. The more influential your post, the greater your moral responsibility. The C.E.O. is more culpable than the cleaning crew.