I bought a B180 for my mother and the main dealer was able to show all the work done to the vehicle from new. If money has been spent on a vehicle, it could show that the owner has taken care of the vehicle, or that the vehicle has had issues.
As with any second hand purchase, you could buy a lemon, or buy a gem.
A few years back, I bought a Mondeo, and even though it suffered from a number of faults when I got rid of it, for the first year of ownership it was faultless.