"Card-stacking" is a technique to exaggerate a position, often through the manipulation or omission of information. For example, when the mayor of a community shows up at an event and uses the opportunity to take over the press to try and gain voters for the upcoming election, that is card-stacking. The purpose of card-stacking is for personal gain.
When card-stacking is used, negatives of a situation are often glossed over while the positives are over-inflated. For example, medication commercials quickly list the potential side effects at the end of a commercial for the drug; however, this is after the majority of the commercial focuses on the potential benefits featuring actors seen as happy and living high-quality lives due to the medication.