Well, vintage Marvel comics usually showcase older characters and story arcs that have become iconic over time. The paper quality and color printing can differ from modern comics. Also, they might have value as collector's items due to their rarity and historical significance.
It's not always straightforward to determine if the signed vintage Marvel comic is real. You need to consider things like the reputation of the seller, the consistency of the signature, and any accompanying documentation or certificates of authenticity.
The rarity and condition of a vintage Marvel comic can greatly increase its value. Also, if it's a key issue or features popular characters, that can drive up the price.
In many aspects, 'The Iceman' is true. It draws inspiration from actual cases and characters, but some artistic liberties might have been taken for dramatic effect.