[monkeh]

Simple thing, Those armed with the common issues, have an excellent bargaining tool.

Willing to put the work in, Like take the car to Volvo to re-screen the screen, Interior out for a deep clean, and to get the navi unit working.
Take a vida/dice unit with you and load up the gun.

"Windscreen is leaking, take £500 off please, that's what Volvo will charge to replace that if/when they break it to re-seal (knowing you'll get it for £249 with their good will gesture), Give me the warranty so I can get the navi unit done etc etc... Why is it saying my s60? It'll need dog guard shocks too £7800-£7500 because you're selling me the lemon"

I notice its already been interfered with, panel gaps on the drivers wing, and on the interior, panels are unclipped and/or broken by the fart lever.

You can either tell them to take it to Volvo for a re-seal prior to sale, and to get the navi unit fixed, then spend a few days stripping it to clean and dry.
My XC was a dog of a car, Literally. Stank of dog urine, coupled with pointing out that the windscreen had de-bonded, drivers door lock knackered, knocked the price down considerably. 3 days of stripping, cleaning with a wet and dry and bio brisk, interior outside drying and I had a compliment from Volvo how nice and clean it was inside.

/edit: Being a coastal car too, I would be checking behind teh fabric wheel arch liners and rear shocks for rot too.