Although mileage wise on the high side for an NB, the owner stated that the car has been regularly serviced at a dealer. I went to see it yesterday evening, so I wasn't able to inspect it very closely. I have, however, noticed that most of the engine cooling hoses were covered in some whitish dusty residue (including small ones connected to the heater). The owner mentioned the radiator has been changed 6 months ago, so this might be related.
Engine oil was seeping through the head cover gasket (firewall end) and the lower side of the engine block and oil sump seemed to be covered in oil/dirt residue. Again, some wet spots were scattered below and around the engine - the low lighting conditions made it difficult to determine their source. I found all these quite off-putting from the start...
During the drive test I noticed the clutch engages quite low after lifting the pedal and the free revving nature of the engine just wasn't there. No signs of clutch slippage, though. While driving, there was also a low rumbling noise present, which I assumed it could be from a wheel bearing or even from the driveshaft. OK-ish shock absorbers and steering and nothing to write home about brakes (although very good state rotors and pads) and gearbox.
Oh, and the air con didn't work - it needs a re-gas at least.
All in all, it wasn't the experience I was after and I felt like something wasn't adding up for a car "regularly serviced". I was expecting the car to feel more alive, more engaging, more entertaining, which it didn't.

I'm interested to know your opinions based on the above scarce description. I definitely want to come back to the car and check it again in proper conditions and armed with your advices.
Many thanks!