When approaching any used car, take a wide walk around it. Look for an fluid drips underneath, tires with low pressure, and any spots of rust. Open the hood and look at fluid levels and the condition of the belts and hoses. If you are able, crawl under the car and look for pitting or weak spots from rust. Look for weak or broken springs as well. Look at the inside portion of the tires for uneven wear. No one wants to replace the tires and pay for an alignment right away.
When looking at a used Alfa Romeo 159, check the clutch repeatedly. The vehicle is known to have a clutch that can be very soft and prone to an expensive failure even in low mileage vehicles. Leave the radio off and listen carefully for a whomp-whomp-whomp sound. This can be an indication of a problem with the o/s drive shaft intermediate universal joint. This issue is nearly impossible to get rid of and can drive some people nearly insane. Also, any strange noises as you turn could indicate an issue in the power steering system. If you hear a noise coming from the power steering, immediately return the car from whence it came and forget about it. If you are buying the car from a dealership, request a cambelt and water pump change before you agree to buy the vehicle. No reason to take a chance with such common repairs.
Buying a used Alfa Romeo 159 can be a great experience. Part of the fun is in the chase, looking for the right vehicle. Along the way you are bound to find a few stinkers that someone is trying to unload on some gullible fool. Use all of your senses while shopping and you should avoid being that fool.

[...] with all used cars, you can not just dive in head first and hope you have bought the right car. There are many things [...]