Most states limit the number of cars that an individual can sell without a dealer's license, or only allow the selling of one's personal car. "Curbstoners" (or "curbsiders" in Canada) are people who ignore these laws and sell multiple cars that frequently have hidden problems in their pasts -- problems that can affect both the safety and the value of these vehicles.
Before buying any used car, you should research the vehicle and the seller. Try to get a vehicle history report.
Be wary of sales conducted from the side of the curb or a vacant lot. Often these vehicles are sold by con men posing as private individual sellers.
When buying a car from the classifieds like Craigslist, do a web search for the phone number and see if any other cars are being sold by someone at the same number. If there are, it's likely a curbstoner.
Title jumping is illegal. Curbstoner sellers due it a lot when they are scamming people into buying bad car and cars that can't be titled to the new buyer.
Oftentimes it is people who are car dealers but do not want to go through the legal issues to become one. I was a curbstoner for years. I was a licensed dealer but I sold cars "on the curb". Not to cheat anyone but to have lower overhead & operating costs.
In most states, the limit is ZERO if you intend to profit from it. The stated limits are often 5 per year. But enforcement is often next to impossible as long as you arent running a car lot out of your yard. There is no computer going to "catch" you if you happen to sell 6 cars in a 12 month period. However, if a person at the local DMV office sees a bunch of people buying cars from you and remembers you, they might look it up and catch you that way. Penalities would likely be zero. They would push you to become licensed to stop dealing so many cars. Whoever wrote all above this is uninformed. There IS a computer to track you. Each state has programs that flag the number of cars titleded by an individual. So when an individual reached the maximum allowed, it may be sent to an investigator. The DMV investigators are also constantly checking Craigslist for duplicate ads by individuals. How? They track by telephone number. Don't be so foolish as to violate the laws of your state. Educate yourself don't believe everythinng you read on sites like this. And don't consider leaving your name off the title when you purchase it from an individual so you can put the next buyer on it. That's called an "open title" and is illegal. It caused tax evasion brecause people doing this are avoiding payment of fees and sales taxes on their purchase. ------------------ Despite what krazycarguy says, my answer is 100% correct and I was a curbstone car dealer for 15+ years. I went many years without a license but pretended I did and the state never caught me. Open titles are risky for a licensed dealer but I did a number of those before the penalties got so bad in my state. The bottom line is worry about making money on the cars you sell. If you can make $800-1200 per car, after 5 cars, you've got $5k profit to decide if you want to get a license or risk it. I risked it a lot of years because the bottom line is, and I got this DIRECT for a higher up in the dealer department of my state, if you begin to cause a problem, they will encourage compliance. You arent going to jail for selling 7 cars in a year. And you wont get huge fines unless you repeatedly ignore things like "cease & desist" orders. I will admit that in my area, curbing cars is harder than it was for a long time. But, Ive long since been out of it. The internet is the new street corner and thats where a lot of curbing gets done. My brother bought his son a car and he bought from a curbstoner who lied about selling it for his sister or some crap. The guy cant be caught because nobody has anything on him. Except a throwaway cell phone #.