I'd say it depends on the accessory - do you want to keep it and put it on the next bike, if so, what's it worth used, what will it cost new, is it worth the time and trouble to remove it, etc.
When I bought my RT (used) it came with bag guards, cylinder head guards, backrest. The seller didn't value them, and so I certainly didn't. I took all that stuff off and sold it, adding PIAAs, Corbin, C.B. w/s, barbacks, Kisan, supplemental brake light, Throttlemeister. When (if) I sell it, I'll probably leave all the electrical stuff and keep the other stuff to either put on the next bike (if it's an RT) or sell them separately.
The LT that I bought (used) had zip options other than a tank bag, which I also removed. Now it also has the PIAAs, C.B. w/s.... damn, this disease never stops, does it? :-)
Life is too short to compromise on your toys.
'08 R1200GS Namabia Orange
'08 335 Coupe
'11 535 Sedan (on order)