Top 10 Warning Signs That You Shouldn't Buy a Used Car

Shopping for a used car? Great! There are plenty of good deals out there. If you're not careful, though, you can wind up with a car that'll pay for your mechanic's new in-ground Olympic-size pool. A thorough review by you, followed by a more in-depth inspection by a reputable mechanic, is an important part of the process. Your mechanic's evaluation will be most important, but there are some hints and clues that even the average Joe or Joanne can pick up on.

What are some telltale signs that you should "lace 'em up and run?" Here's our list.

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P.S. You might notice that this is actually a Top 11 list. Math was never our strong suit.

1. Lack of Repair Records

If the seller can't show you accurate repair records, you should assume the car hasn't been reliably serviced. Approach the condition of the car with plenty of skepticism, and have it thoroughly checked out by a reliable mechanic. On the flip side, a detailed set of records is a great indication that the owner has taken maintenance and repair seriously and that car may have been well cared for.

2. Obvious Signs of Abuse and Neglect

Dings, dents, strong odors and ugly stains are all signs that someone has not been treating the car well. By themselves, superficial signs of neglect are no big deal, but a person who doesn't care what his car looks like or smells like may not care about its mechanical condition, either.

3. Recent Evidence of Mechanical Band-Aids

Recent detailing by itself isn't a reason not to buy a car. In fact, all it may mean is that the owner is wisely tidying up the car up before sale. But keep your eyes open that the seller is trying to obscure defects. A recently cleaned engine compartment, for example, could hide evidence of an engine that's leaking oil badly. A receipt in the trunk for a carton of Restore engine treatment could be a clue that an engine has seen better days.

4. High-Performance Cars

Performance cars are not good things to buy used. Think of the profile of the average customer for these cars. Do you think a buyer of a new Camaro or Nissan 370Z is interested in comfort, cabin accoutrements or the number of cupholders? Hardly. They're interested in seeing what the car "can do" — and that means plenty of stress on the engine, suspension and other expensive systems. (By the way, isn't that why you're interested in that type of car, too?) So don't expect a used performance car to have been treated gently.

5. Smokers

We wouldn't buy a used car from a smoker for two reasons. First, smoking is reckless behavior. Second, it suggests the owner might be reckless with regards to repair and maintenance.

Even more important, there's the stink. Even if the smell is only faint, you might want to walk away. First of all, the owner probably left the windows open for a week before selling it, and probably emptied a 55-gallon drum of Febreze on the upholstery. That's as good as it's ever going to smell. It will only get worse once you roll up the windows and take it home. And the smell will never, ever go away — a bitter reality that's true for any strong odor. And, over time, the smell of cigarettes will permeate everything you own that travels with you in your car: your clothes, your gym bag … even the apps on your iPhone.

Look for the telltale signs of burn holes in the upholstery, evidence of cigarettes extinguished in the ashtray and the scent of English Leather cologne being used to mask the smell.

By the way, if you're a smoker, buying a car that's been used by a smoker is a chance to get a good deal. Most non-smokers won't want it, and what do you care if you burn another hole in the upholstery?

There are a few warning signs that are easier for your mechanic to check than for you to check. Here are three we consider to be especially important:

6. Oil/Transmission Fluid

Checking the oil is a good way to tell if the car you're considering has been well maintained. Since it's hard to judge for an oil condition, we'd suggest you ask your mechanic for guidance. He'll check to see if the oil is absolutely coal black in color and if it feels gritty. If you're really serious about checking the condition of the oil, send it out for analysis or grab a Lubricheck.

The condition of the transmission fluid is an even better indicator of upkeep, since only the more conscientious car owners will remember to change it on schedule. Your mechanic will look for the telltale signs a dark brown color and a burnt odor that are giveaways of transmission fluid that needs to be changed — or worse, an impending transmission replacement.

7. Coolant

Every cooling system will have an overflow reservoir next to the radiator. Your mechanic should check the reservoir for indications of debris in the fluid, which would indicate a lack of service. The color of the coolant used to be a good guide as to whether it was being replaced on a regular basis. But because there are now so many different types of coolant on the market, that's no longer a good maintenance indicator.

8. Accident Damage

Everyone has mishaps, so it's not a deal-breaker if the car you're considering has been in an accident. Almost every car "of a certain age" has been in some kind of fender bender. However, if your mechanic sees that the car has had all four corners repaired, that might be an indication that the vehicle has been driven by a reckless driver who is probably reckless about maintenance, too. Or, if the car has been in a particularly serious accident, you can have unexpected problems later on, like electrical gremlins from pinched wires or uneven tire wear due to a bent frame and inability to align the wheels. Have someone who knows auto body repair check the quality of the job — what's visible to the eye is also an indicator of the care given to the work that you can't see. You can bet that the quality won't get better when you get to the stuff you can't see.

There are a few warning signs that are, we admit, completely prejudicial, but we're including them because they may have validity in some cases.

9. The Age of the Owner

We wouldn't buy a car from anyone younger than 30. Why? Because we're well over 30 now, and we remember exactly how we drove when we were in our 20s. Of course, this measure tends to be a sliding scale since everyone younger than you is reckless and imprudent, right?

10. Certain Bumper Stickers

Bumper stickers say a lot about a car owner's personality. For example, which car would you rather buy, all things being equal: the one with the "I heart knitting" on the bumper, or the car with a collage of "Ask Me About My Demolition Derby Victories," "Metallica 4Ever" and "Just Released from Supermax" adorning the trunk?

11. Radio Station Presets

Like bumper stickers, the radio stations a car owner listens to says a lot about how they approach life. If you turn on the radio and the presets make the windows rattle, odds are the driver isn't the sedate, drove-only-to-church-on-Sunday type.

© Cars.com 05/1/2013