How to tell what kind of paint was used on house?

[Teacher Terry]

Walt, the painter who gave us the estimate said they were required to remove it and he actually recommended that we paint over it ourselves.

 

[Bongleur]

The stains are on the bottom third of the walls - where sprinklers soaked them, no doubt for years. Lawn sprinklers here use shallow non-potable wells, that have goodness knows what in them.

You could repaint only that bottom third, and hide the shade difference with a wide stripe of a festive color. Or even do the bottom in an earth tone that would hide future stains.