The Alfa has a better sound than a Ferrari, (which do sound good but at too high a RPM the sound very tinny and rattle) An alfa V6 doesn't, its deeper and more aggressive on full throttle... Its an engine note like no other car so a waste of time trying to compare or explain. You have to listen to one in the flesh under load
Alfa's don't rot, come on, you should know by now that they are galvanised and "rot" less than many other marques of similar age like VAG/VW for example.
A V6 GTV will sound very similar to any Alfa V6, same engine just different capacities... 2.5, 3.0, 3.2
what to look for?
Far better to get a higher mileage car that has had the cambelt/ waterpump done than a lower mileage which hasn't...
Clutches last about 60,000 but are a pain to swap so get one with a recent clutch change
the rear bank of spark plugs tend to get neglected because they take longer to get out so make sure you see bills for them.
Oil services too as the oil filter is very difficult to remove and replace due to its location.
Apart from that, they are pretty much bullet proof and can take a hell of a lot of hammer if looked after...
In fact, I wouldn't personally put any TS or a JTD through the same amount of torture that I do with my V6, I know through my own experience they wouldn't take that kind of regular abuse and say "thank you very much, can I have some more please".... The most fun I have had in an Alfa has been with a V6