The only problem with dunking parts is that you can never get rid of all of the solvent. They spray with neutralizers, but eventually some of the caustic solution will weep out of the cracks onto your new paint. This is more of a problem on unibody cars. Plastic media blasting has some similar problems - you'll always find plastic media somewhere in the car. Probably the least problematic is the baking soda blasting. Any leftover soda will protect the metal from rusting, and will also wash away with water.

A fairly new process is baking the parts in a large oven - it gets rid of the paint, primer and bondo and it stress relieves the parts.