I think if a classics CHUG collection has lost its appeal, selling should be the last resort. The alternative is to try and reinvent it by changing or rearranging a display. Also cleaning and dusting will give a fresh outlook and satisfaction.
Don't be afraid to cull some of the deadwood in the collection, things that just don't fit, and just put them aside for now.
If you are considering collecting Combiner wars, I think classics CHUG collecting can be good again. All those classics figures will look great displayed with combiners!