cleanliness, (was it well maintained?)
function, does everything work- wheel turn, needle go up & down, electical components in good condition, belt without cracks?
decals in place
price.
i love the old machines but am not interested in having to spend a bunch of extra money to restore them- if i'm going to buy one i want it usable- and (hazard free) i don't want a fire hazard- dangerous piece of equipment- so the cords must be in good shape- having some attachments, assessories is nice too-