What turns clear liquid soap blue? Liquid soap that sits in metal pump handles turns blue after a week or so, as in this photo comparing the soap in its initial clear state and then after pumping from the dispenser.



The pumps are presumably brass with either nickel or chrome electroplating on the exterior.  Can't say for sure whether or to what degree the interior where the soap makes contact is plated.  They have been in use for years.

The ingredients of this particular soap are:


water
sodium laureth sulfate
cocamidopropyl betaine
decyl glucoside
sodium chloride
"fragrance"
DMDM hydantoin
polyquaternium-7
tetrasodium EDTA
citric acid
sodium sulfate
PEG-120 methyl glucose dioleate
PEG-7 glyceryl cocoate
poloxamer 124
D&amp;C red #33
FD&amp;C blue #1
The color of the precipitate is strongly reminiscent of copper(II) hydroxide. I hypothesize:


Chloride corrosion of copper from exposed brass (ref 1 || ref 2)

a. Per ref 2 above, sulfate may also participate
Alkaline precipitation of $\ce{Cu(OH)2}$ in the neutrally-buffered soap
Insufficient $\ce{Na_4EDTA}$ to complex the amount of $\ce{Cu}$ corroded from the brass


It's also possible the blue material is $\ce{Ni(II)}$ complexed in such a way that its color is changed from the typical green-blue of $\ce{Ni(OH)2}$.