There are some additional rules that extend beyond liability that buyers and sellers should be aware of that protect them from being misled or manipulated by the other party.
Canceling an agreement
Buyers and sellers have the right to cancel an agreement if the other party doesn't uphold their end of the deal.  Sellers can withhold the item until the buyer meets all the contingencies and even stop a delivery already in transit. If the agreement ultimately falls through, the seller has the option to collect any damages and resell the item. The Federal Trade Commission (FTC) has the "Cooling-Off Rule" that protects buyers in some circumstances, such as purchases made in high-pressure situations. The rule gives a buyer three business days to change their mind about a purchase. However, contrary to popular belief, the Cooling-Off Rule doesn't cover motor vehicle purchases. A buyer should review what the Cooling-Off Rule covers and never make assumptions before making a purchase. Connecticut, California, Massachusetts, Minnesota, New Jersey, New Mexico, and New York have lemon laws to protect buyers if they purchase a defective vehicle, but even these laws are difficult to enforce in many cases.
Warranties
A warranty is typically an agreement between the manufacturer or retailer and the original purchaser (the seller). A reseller likely doesn't have the authority to extend the warranty to a new owner, and the retailer's obligations are usually only to the person with whom they made the original transaction. Buyers and sellers should be aware of two common types of warranties: Express Warranties and Implied Warranties. An express warranty is basically a written or verbal guarantee that an item will provide a specific level of reliability and quality. If it doesn’t, the manufacturer will fix or replace the item free of charge. An implied warranty guarantees an item will, at a minimum, work as claimed. This warranty covers used items as well. For example, if a recently purchased lawnmower's blades don't spin fast enough to cut grass, the item isn't performing what it claims to do and is covered under the implied warranty.
Advertising
When reselling a product, a seller shouldn't simply copy and paste a retailer's advertisements for their own ad. Any ads about the item should accurately reflect its current condition so a buyer has the best possible impression of what they might purchase. It's generally acceptable for the seller to give an opinion about the item, but it needs to align with an accurate description of the product. For instance, a seller can give the opinion that the tractor they're selling runs well because that isn't a measurable statement that can easily be proven fake. It's more of a sales pitch than anything else.