I've always welcomed fire restoration jobs if it is through a fire restoration company. It can be very (and I do mean "very") profitable.
Each job is a little different depending on the damage and what is being repaired. Mostly it is cleaning of oils, re-varnishing, wiping down the frames with various products, reframing severely damaged frames, fitting, refitting, new mats, etc. Usually 10 - 50 pieces.
I like the idea of charging for an estimate fully applicable to the work if working with an individual. If you work with a fire restoration company and develop an on-going relationship, estimates are not necessary. Insurance generally pays the bill and the fire restoration company pays you upon pick-up or delivery.
Don't refuse the good work, just realize that there can be quite a bit of soot, smell, etc. and you must prep your shop for the dirt and clean up afterwards. Of course this is billable time too.
Dave Makielski