Its all relative..... Its very difficult / expensive to find totally NEVER rust free car ... we are talking about 30 year old car. I THINK most of these cars, when they say "rust free" or "California car" have gone through some kind of rust prevention in some area of the car in its life span. Obviously the rust was never severer or deeply penetrated, considered minor stuff. Moral of the story, don't let small bubbles scare you. But you have to take care of the problem areas soon. I THINK the spare tire well problem shouldn't be that difficult or expensive to fix. Also look inside / through the glove box, look inside the tire wells / strut towers. See if the original tar paper / seals are on the strut towers under the hood, floor pans. If you can, pull the back seats out.... The interior trim parts are rare and will cost.... Good luck