Original owner? Service record? If you can, before Thursday, get the VIN on the bike and check out it's service history at dealership or shop. If not original owner ( see title), see if you can contact previous owners. Has the bike ever been down/crashed?
Whenever I've sold bikes, unless to a friend or relative, I've never allowed a test drive. But I offer to ride the bike WITH the potential buyer next to me/behind so they hear/see it's handling, engine sounds, etc.
Check out brake wear, tire wear (even?) evidence of leakages, how the the various seals? Are the plugs fouled?, clutch pull, chain tension/wear, how rich is the exhaust running? How does it run through the gears when shifted? Electrical system working properly?
OK, I'm only on my first cup of coffee...I'm sure there's more...