Wow serious subject! I been there before and know that the mention of "cleaning" can bring with it a barrage of decent from opinion based on academic study. Here is my slant on it
I appreciate and deeply respect the people who are involved in most of these studies. Any that I read through the professional journals or publications from RIT, AIC or other credible sources, I will weigh along with everything else that I've ever read or know from personal experience. Unfortunately I've found that that respect is not always returned for those who are on the firing line doing the day to day work in actual conservation. Like medicine, you would never take anything if you followed every bit of documentation written.
I would hope that the two sides can be brought closer with forums like this one dedicated to the Retouching Pro but open to people who have a foot in both worlds (so far at least)! Hopefully creating a new middle ground between those who need to learn that you don't clean photos with spiced up gasoline and those who think photos should be viewed with a fifteen watt light bulb not more often than once every 20 years or it will be the end of civilization as we know it..
I had to smile when I read your post - the "aqueous treatment" the last batch of albumins I finished working on a few months back was from a drain overflow that came down from the floor above onto a work table with prints being laid out for cataloging. It went unnoticed for a week or more and they got a good soaking in sewer water! Nobody questioned techniques for cleaning at that point!
I may get into more disaster recovery work than most restorers because I like the challenge of the work, but that job illustrates the point that - at the working level - decisions have to be based on the prints in front of you and applying the best of your knowledge along with common sense.
A critical point in your post, if the treatment isn't going to do anything to remove the stains or contaminates, no, I wouldn't clean them, but that determination will be based on a check under a 30 power magnifier to see what if any emulsion breaks are there and then testing with a q-tip to see if I am lifting anything - and if so what.
We were talking about money - and income rises with knowledge in any profession. I think this profession is underrated because people think of it as a "craft". It can go places if people start seeing themselves as true professionals. Working with historic materials is not a walk in the park, however, for any who are interested, there are some great forums where in depth information is available including a new one for photo conservators at
http://groups.yahoo.com/group/photoconservation/ - It's moderated by Luis Nadeau who will NOT entertain questions about digital! I'm sure most of you are familiar with Conservation Online If not it's a resource for Conservation Professionals from the Preservation Department of Stanford University Libraries that can be found at
http://palimpsest.stanford.edu/ As far as I know anyone can make inquiries but only qualified professionals can post so the data base has some of the best and most current information available.
Jim Conway