Reading through all the contributions it strikes me that with the possible exception of the yellow flowers all the uses of the word yellow signify something that is "not very nice" and to be avoded ie plague, disease or generally socially unacceptable in the cases of prostitution etc.. There is also of course the cowardly use of the colour. I wonder why the colour Yellow in particular has been singled out for this usage. Could it be that unlike red/green/blue in colour blindness it is less likely to be confused with another colour so is more readily identifiable and therefore by association its meaning less likely to be misunderstood. Melodeon