Usually, in a perfectly inelastic collision, maximum amount of KE is lost. I guess it depends on the rigidity of that object collision if any KE at all will be converted to work done to deform.
Assume: coefficient of restitution = 0, no surface friction or air resistance.
An example of this phenomenon, I can think of, is throwing a lump of clay onto a wall; at the end both become stationary, meaning KE = 0. Sometimes, this really confuses me, because the initial sum of momentum is not equal to the final sum.