cars stored winters from within the rust belt are usually a totally different story FWIW but winter and salt and rust are BAD BAD BAD
HOWEVER, if not properly stored, or stored outside, then rusted bolts will happen still
..and another thing people don't think about when storing a car.. if you store your summer only car next to your daily driver in a 2-car garage, you are still exposing your 'baby' to salty wet conditions every time you drive your salt-encrusted car in and out of the garage!
I paid big money to keep my porsche in proper climate controlled winter storage away from all the elements and now have it living down in Phoenix (saves me over $2k a year in storage fees!) so it is indeed rust free (but more the exception to the rule is my guess)
The bottom line is you have to do your homework buying a car these days (especially cars 10+ years old IMHO)... ..and that is the bottom line