Ethics in Advertising

We in advertising spend a fair amount of time dealing with what outsiders might call ethical choices, very few of ever fall into the black or white column.  Our job is to increase consumer awareness for our clients and, subsequently, increase sales.  This challenge often creates “gray” areas; how do we balance the need for greater sales with the desire to avoid the old bait and switch methods? I’ve seen many approaches (celebrity endorsements, product comparison, price comparison, selling a dream or lifestyle, selling with sex, selling sentiment), all of which present their own ethics considerations.
Telling the truth always seems to be the best answer, but how to paint the comparison pictures or draw on human emotion without crossing that line of right and wrong is our challenge.  And, this challenge becomes even more monumental when our competitors use unethical methods. I recently came across a very good article here that explains these very issues, but have not, as of yet, found the true solution.  I tend to trust my “gut” and try to tell the truth. Anyone out there have a better approach?