As with all cars, it pays to check the bodywork in key areas before buying. Here are the main points to be aware of with the F355.
Both Berlinetta and GTS have 'butress' designs at the rear. Where the buttresses meet the rear wing there is a seam which runs lengthways along the car (see picture). Pretty much every vehicle (except for Spiders) will experience corrosion along this seam. Theory has it that this corrosion is caused by a number of factors such as stresses from driving the car hard, movement in the body when the engine is dropped for the cambelt service, or moisture in the seam from when the car was put together.
Whatever the truth about the cause, owners should expect to see small imperfections under the surface of the paint along this seam, which will gradually get worse over time. Dealers are well used to the problem and it is common for the rear wings to be resprayed. This can be identified by a characteristic blend line where the buttress meets the roof. You will be able to spot this blend line more easily under incandescent lighting. Despite resprays, the problem does return again every few years.
Due to the very low front end, stone chips are a fact of life. You should expect to see these on the bumper and even the bonnet on all vehicles. Any car with no chips whatsoever has had a respray. This is nothing to worry about in itself unless there are other signs of accident damage, as it is common for owners to get a bumper respray every couple of years to cover up stone chips. Some owners use 3M type bumper protection film, but opinion is certainly divided from a looks perspective; although the final look seems in the main to be down to the ability of the installer. These protective films have a habit of picking up dirt along their edge, which doesn't look too good after a while. Bascially, you can't win with stone chips.