I find glue traps as inhumane, the mice get trapped and they die an agonizing slow death. Once trapped they cannot be detached from the glue bed without their skin being ripped off their bodies.
Usually when they were caught in the trap, I woke up to them squeaking or thrashing around within a few minutes to at most hours of them being caught and drowned them by placing the trap upside down in water.
I agree it is not a merciful way to go, but they do not make good houseguests and other methods proved ineffective.
