I have seen this happen on even well cared for games - seems the less played sometimes the more they rust...not sure if that's from *lack* of heat with no lamps etc?

I would not consider this something to judge a game by without other issues suggesting a lack of maintenance or other issues.

Removing will generally remove the blue colour. You can buy re-bluing agents. You can also often buy re-made ones, but riveting can be an issue.