Interesting thread...
While no one should be recommending ingesting dangerous chemicals, it is interesting to note that the human tongue is apparently quite a sensitive instrument and can (and was and is) pressed into service for various types of chemical analyses.
If I remember correctly, Galen wrote about tasting his patients urine as a diagnostic tool; if it was too sweet - diabetes! I seem to remember lots of alchemists and later chemists using the taste test on many different compounds.
Most recently, on my flight back to Vienna a couple of weeks ago, I watched one of the nature programs on the in-flight entertainment system. Lo and behold, there was the naturalist/hero/tarzan-cross wrestling giant salamanders of all types. As a grand finale to the capture, he tasted the mucous coating the various species to determine the degree of toxicity (and spit it out, of course). This practice he pointed out, was not his invention, but taken from researchers in the rain forest of Amazonia who use the same kind of taste-test to determine the relative toxicities of the many kinds of poison-arrow frogs.
In the above context, tasting a little wash water dripping from a print to see if there is any slight taste of very, very dilute fixer present seems quite benign to me... I think I'm gonna try it! And spit out the water, of course. I'll let you know if I turn blue
Happy tasting!
Doremus
www.DoremusScudder.com