Some things to look for on a Honda Big Ruckus:
Cosmetic condition is king. Missing or damaged plastics or buggered paint is a major downer. Make sure the fork seals are not leaking. Check that all the electrical works as intended. Bring along a bright flashlight and a clean rag so you can see and wipe off any grease. Check the outer edges of the handgrips for scrapes or scratches.
When a Big Ruckus crashes or tips over, the first part to contact the ground is the footrest.
Check both footrests for alignment and for repairs from being previously bent or scratched.
Looking down from above, if the footrests are not equadistant from the frame you need to look closely at the crossmember welds underneath the Scooter where the footrests bolt to the lower part of the frame tubing.
If crashed hard enough, the footrest can twist the lower frame which can break the weld at the crossmember.
I looked at one that had been previously crashed and that exact situation was evident, once I wiped off the grime.
The oem rear shock is designed for a 130lb rider and will need to be replaced with a YSS, Bitubo, or Ohlins.
An expensive fix but the Scooter will ride and handle 100% better than stock.
They come stock with six 26G rollers (156G total), replace with six 21G Honda Reflex rollers or Dr Pulley sliders and enjoy a lot better acceleration.
The Carburetor is jetted lean compared to other similar Honda 250cc Scooters, upjet accordingly.
Totalruckus has the 411 on the Honda Big Ruckus.