I read this thread last night and agreed, I wouldn't dunk a model. This morning I've taken an old "experimenter" with its odd paint and
decals in strange places, given it ten minutes in some barely luke warm,mildly soapy water and pulled it out. There doesn't seem to be any problem with the paint (acrylic) or the areas of original varnish,which was a silk coat but I'm not sure which.It's certainly a lot cleaner!
Maybe it is possible as a last resort but as someone else said test first.
My favourite duster is a blusher brush as per Tony's tip,just don't nick SWMBO's favourite unless you want to develop a sudden limp!
Steve