here is a neat experiment…
take a can of cream of mushroom soup. cook as directed, but add a few drops of blue food colouring
Most people find this completely inedible, as flavour/aroma expectations do not “add up” with visual expectations.
FML
Oh yes! I completely freaked out my younger sisters by adding blue food coloring to the milk–nobody would drink it! They did drink the pink milk, though, perhaps that’s less scary…
Of course, the green = mild and fresh expectation goes right out the window when you discover wasabi…
I drank blue milk once. It was a carton of Nestle strawberry milk; it was supposed to be pink, of course, but apparently something went wrong and only the blue coloring was added. Either they ran out of red coloring or the lines clogged or something. Anyway, it tasted fine.
If you think about it, pink hearts, yellow moons, orange stars, and green clovers makes sense.
There are no orange stars. 
I remember reading the reslts of a food color/taste questionnaire once. The once question I remember was “Do different flavors of red jello have a separate, distinctive taste?” So many said yes, so may said no, and 18% just stood there quivering, like the jello.
On a related note, I remember years back a study performed on the effects of different-coloured lighting on the appetites of restaurant patrons. According to the study, there was a significant difference in how much someone consumed when the ambient lighting was one particular colour over another. As I recall, green-tinted lighting tended to reduce one’s appetite. (I don’t remember which ones if any increased appetite, but neutral (white) lighting had no discernible effect) This is almost certainly an environmental extension of the colour=flavour association, though given the results it is possible too that, where food is concerned, an association between green and spoiled food (mold) is at work here, too.
Yeah, that’s why spinach, lettuce, broccoli, string beans, limes, cucumbers and honeydew melons are sooo unpopular.
I sometimes bring pistachio muffins to work. People freak out. “But they’re GREEN.” I say “They are pistachio.” Damn good too.
I think it had more to do with the fact that everything had a green tint to it, which would definitely look a little off-putting if your meal contained steak. People expect some veggies to be green. Meat, not so much.
Dave Stewart (of Eurythmics) admitted he liked eating blue (or was it green?) mashed potatoes in an interview, once.