Okay, so according to the DVLA the bike is currently SORN and the MoT ran out on the 17th May this year.
At it's last MoT 18/05/18 it had covered 22,122 miles so not a massive amount since new assuming it is genuine.
Going over the mileage history from MoT records on file it covered just a few hundred a year back to 2014 and from then back to 2006 anywhere between 1000 to a tad over 3000 per year so I would say about average for a UK bike used on sunny weekends only.
https://www.check-mot.service.gov.uk/
If that was indeed the case then you would think the general condition should be good but it depends on the more recent years whether neglect and lack of use has taken it's toll.
Generally speaking, Ducati's don't like being sat around unused so evidence of services would be a nice reassurance of it being cared for. Especially this last year where it hasn't been used at all- if it was just parked up and left that would be the worry. Ethanol in fuel can wreck havoc allowing water to sit in the bottom of the fuel tank slowly rotting it, not to mention the gummed up injectors and most likely sticky brake caliper pistons from moisture in the air.
However, if it was drained of fuel, the tank lightly oiled inside and the battery removed before being cleaned, wrapped up and stored in a nice dry garage it may well be not too bad.
That being said, almost anything can be fixed (even Triggers' broom
) or restored (just look at Albie's '93 900) and if this one has the sentimental reasons for you wanting it then it is probably worth it to you for that alone assuming a price can be agreed.
Personally, I'd say don't worry about if the belts were changed in line with service intervals- a years lay up is enough to factor in a pair as part of a full service with a valve check to give you a starting point for future maintenance records.
Because I'm a bit of a anorak over such things it would be nice if it had the original Owners and Service books but again these can be picked up via eBay etc. but one thing I would be wanting is the all important 'Red key' which I believe it should have (I'm sure an S4 owner will correct me if this is wrong?) to over-ride the factory immobiliser etc. should you encounter any electrical problems.
Other than that- get it and work through any issues you encounter as and when. Plus it will make a great thread here for us all to read about your progress