Chances are, your friendly RV
salesman never told you about galvanic corrosion. This is the process by which
dissimilar metals (i.e. aluminum and stainless steel) actually form a battery
and start corroding.
Chrome and stainless steel
hardware, hinges, aluminum window casings and railings are under constant attack
from ultraviolet radiation and acid rain. If not properly cared for, they will
pit and corrode.