Hi Jack,
With me it all about how much if any original paint is left on the machine, this one had no original paint anywhere and was in quite a sad state all around. The once chrome bars are very rusty and overpainted with one of the locking bars rusted clean through, the base was dented in badly at the front and repainted plain green with a not so matching orange cowl.
If the machine has good decals but poor paint I will just cosmetically tidy it up and do the mechanical side of things to bring it back to running condition. The ones I love to get are the ones that just need a wash and a service.