In that case make sure all documents tie up with bike and owner. Check Vin and engine number are the ones on the V5, check service records, mot etc. A well looked after bike should be obvious, regular oil changes etc. and the paper trail to back it up. Take dip stick out and feel the oil between your figures, is it smooth or gritty. Check brake pads have plenty of wear left on them. Get the owner to tell you about their experience with the bike, how long owned, from new? etc. etc. Hope it is as you expect. Edit: just realised you were going today so maybe this is too late. Did you get it?