Do you think the color(s) of dishes affect the appetite?!

Yes. As already said red make you hungry. That is one of the reason the older restaurants from the 40's & 50's all used red booths, red carpet etc. There plates were not red but there was enough red in the room to choke a horse so there was no need for the plate being red. Besides they wanted you to be hungry and to order lots of food before the plates arrived.
Presentation of the food is more important then the plate. Most cooks prefer white backgrounds to show off their color choices of food

White actually shows off food to it's best
Look at the cookery programmes
99% of chefs use white

Blue usually makes you crave things more
red makes you hungry
and I think yellow makes you feel not hungry

I think bright colors are appetizing.?

Red actually has been scientifically proven to cause an appetite. :)

For me it all depends what is on the plate,,,not the color of such plate....