You come across an advertisement that says the car dealership down the street has a “No payments for 12 months” promo. Your income is a little unpredictable right now, but you have a few prospects so it would be perfect for you. You pick up the nice convertible you saw as you were driving buy.
After a few weeks when you start to get a feel for your vehicle, you get a letter from the dealership telling you the first payment is due. You call immediately to dispute the letter, but they tell you the promotion was only available for the week previous. You check the ad again and there are no dates so you have no way of holding them to it.
How to avoid: always ask the dealership to add in the contract “No payments due until…” Verbal agreements are not enough.