The kind of sap that acacia trees produce is a gum...similar to what they use in ice cream or chewing gum, sweet and syrupy. Gum arabic (which you may have seen on food labels) comes from certain species of acacia. Gums are fat or water soluble (meaning they will break down in those substances, which are found in the body). Some gums can be toxic
as well...a glider doesn't just make it's home in just ANY species of Eucalyptus or Acacia...only certain species of them (there are hundreds). And Eucalyptus is toxic
to humans-you or I certainly wouldn't want to eat it.
The saps from trees like pine and cedar are known as resins. According to Webster's (so I can give you a better idea), resins are "any of various solid or semisolid, viscous, usually clear or translucent, yellowish or browninsh organic substances exuded from various plants and trees; natural resins are soluble in ether, alcohol, etc., and are used in varnishes and lacquers, as modifiers in synthetic plastics, etc."
Animals (including people) do not produce ether or alcohol in order to break down resins. They are indigestible, and poisonous. They also give off fumes, that also contain these resins, that can be breathed in, causing problems in the airway and building up toxins in the bloodstream when it enters through the lungs, since the body cannot break it down or eliminate it. Gliders don't make their homes in resin bearing trees in the wild.
The reason resins are used in varnishes and lacquers (think shiny furniture) is because if it gets wet, it won't come off. Resins are also used to make violin bows work-it's what is rubbed on the bow to make it "tacky" and produce the sound of a string instrument. It takes ether or alcohol, or a great deal of friction (ie rubbing or sandpaper) to remove it, and most people don't go spilling those around their house.
Anyway, I hope this helps. If anyone has anything to add, you're more than welcome...this is just the basics. I am an expert on resins by no means.