In a study by George Loewenstein et al1, they found that when advisors were providing disclosure of conflict of interest, they allowed themselves to give more biased advice to the advisees.
Here are the mechanisms at work to explain this behavior, from their paper:
Two mechanisms involved are strategic exaggeration (the tendency to provide more biased advice to counteract anticipated discounting) and moral licensing (the often unconscious feeling that biased advice is justifiable because the advisee has been warned).
They apply this effect to physicians, but an obvious field where it can apply is also financial planning and in general any field where the advisor may have some interest in the decision made by the advisee.
Note: this item is classified as a research item and not a mechanism because the results in question, to my best knowledge, haven’t yet been replicated enough to consider it valid without any doubt. See this post for an explanation.