Ride, comfort and safety are important consideration point when buying a new or used vehicle. You should visually inspect the car to ensure it is sitting level, front to back. If the front or back are lower, it may be that the springs are worn. You should first check the shock absorbers and springs. The easy test for worn front and rear shocks is to bounce the front and back of vehicle, applying weight to the corners, not the center of the hood or trunk (which may dent!). If the vehicle bounces more than one time, the cost of replacing the shocks and/or struts needs to be considered. If the car bounces multiple times, visually inspect the shocks or struts for visible oil or wetness, which may also indicate worn components, affecting your safety and comfort.
This is even more important with air ride suspension, as the components can be very involved and very costly to repair.
Look at the tires for worn outer edges, which usually indicates a front end that is out of alignment and /or has worn front-end components. Deduct money for this, since you should not do an alignment on worn tires.
When test driving the vehicle, check for ride comfort and stability. The vehicle should neither be bouncy nor unstable, which are signs of worn shocks or struts. When cornering, the vehicle should not lean excessively. An if it pulls to the left or right while being driven, could indicate the front end that is out of alignment or that the tires are inflated with uneven pressure. Does the car shimmy or vibrate? The front of the vehicle or the steering wheel will shake, especially approaching highway speeds, when the front tires are out of balance A vehicle with a properly maintained front end will have front tires which wear evenly across the tread.