Myth: high mileage means a bad car. Ex-fleet cars are often higher mileage, but most of those miles are motorway miles, with less wear on the clutch, brakes and suspension than urban stop-start mileage. A 70k-mile ex-fleet car can be in better mechanical health than a 35k-mile urban runaround.
Myth: company cars get thrashed. The opposite is usually true. Company-car drivers know the car is on a service contract with strict damage-recharge policies. The cars come back maintained, washed and on time.
Myth: lease cars aren't looked after. End-of-contract return inspections come with real money attached: missed services, panel damage and tyre wear all trigger recharges to the lessee. The economic incentive runs in favour of maintaining the car well.