Brownells used to sell a water-soluable oil to kill "bleed-out", which is the bluing salts trapped in crevices you cant reach (ex: the threads in a barreled action). When we would blue we would let the parts sit for a few days and address any bleed-out issues. Break free and a toothbrush was also our weapon of choice.
MOST shops these days use powered equipment to polish parts, since polishing is very time consuming to do. A 4-station powered polishing rig works pretty well, and you can have all four wheels rigged up with 240, 400, 500, and 555 wheels ready to go. I spent a lot of "quality" time in front of one.
Smith and Wesson estimates it takes 10-15 years to get a polisher up to speed. I did it nearly every day for four years, and I can tell you its hard to do well, even with the right gear. It really demands attention to detail.
If you want to really get picky about polishing, start looking closely at new or like new guns, and then look at someones sporterized Mauser that bubba did. Look down the length of the barrel with some light coming the other way- look for waves, and irregular patterns. Look down the flats on a Winchester '94 receiver for dished out screw holes. Look at the trigger guard on Auto-5's for pitting that someone didnt address since they couldnt figure out how to get in there. Polishing isnt so much about being "shiny" as it is the proper grit and straight lines.
Like anything else, you get what you pay for. Find someone who really knows what theyre doing, not just someone who CAN blue. I'd also ask to see examples of whats about to be picked up. Cheap bluing is like cheap body work on a car- not worth it.