You’ll pay big bucks for an early glassfibre-bodied 308, but even the 1977-on steel cars have a rustproof plastic floorpan, so check for rot in the tubular steel frame.
Cavities like the headlamp pods and spare wheel well are known rust incubators. Bonnets, meanwhile, can often be distorted. All bodywork is expensive to remedy if it’s been abused.
The alloy wheels on these cars are intrinsic to the whole package but, if they’re porous, they’re going to be hugely costly to replace. Often, though, unsightliness on these cars is restricted to nothing more than peeling paint.