Most oral AAS are metabolized in the liver, and the 17aa structure that makes them highly bioavailable causes stress on the liver as the liver tries to break the substance down. However, var is metabolized mostly in the kidneys and beause of this causes very little stress on the liver. Now, many UG pharms that produce var sometimes cut their var with other compounds, or fake their var entirely. Because of this, UG var can cause liver stress because of the other compounds it is cut with.
Now sublingual applications are designed to allow the substance to get to the blood stream directly - either to bypass the liver's first pass breakdown, or for other bioavailability reasons. However, since var doesn't hit the liver much, it's kinda a waste.