Accuracy is down to the skill of the machinist
Does that mean a good machinist can get accuracy out of a dodgy lathe?
Yes most lathes and mills wear around the centre of the travel, just knowing that helps. If I were to look at buying a used lathe I would arrive with a reasonable size hollow bar or rod and take a test cut with the cross slide locked and longditudinal power feed on. Then mic around the centre of the bar, Any change in OD will have to be wear in the slideways, you have to go up to tool room (Moriseki etc) lathes to get them not to cut a taper.
Marc the round columns have a problem stayng on centre when the head is raised or lowered. If it cuts on the backcut the head isn't straight.