Yes, red-green color-blindness affects about 2% of the population - and therefore 4% of men (because the color-blind gene is recessive in women). It is a good reason against the green clubs. The orange diamonds are no more of problem to them than the red ones, I imagine. I want to understand who put the black-red-orange-green foursome into play. Just about all the bidding boxes I see use these four suit colors. I am researching this subject. Here in Europe I have played with decks that had orange diamonds and gray clubs which I think you can find in Germany and in Spain. That seems like the best solution for the moment. Personally I want 4-color cards to become the standard. I do not like having two red suits.