It's a transactional relationship. I have had a few candidates pull out after signing for various reasons (some personal issues, some for better offers). If they apply a year later, I would likely still give them an offer. There are no "permanent black marks" on you, at worst it is a note in your candidate CRM in one specific company that won't follow you elsewhere and won't impact you at that company after 12 months.
> Most companies won't _really_ care if you sign and then rescind your acceptance if you get a better offer.
What? Of course they care - finding good candidates is an expensive, labor intensive process.