If atmospheric CO2 was visible to the naked eye would that make a difference?

Right wing radio dummies say that the greenhouse effect isn't happening and if it is it's 'natural'. If people could see CO2 gas exiting cars, trucks and power plants could these paid spokesman for the oil and coal industries be able to get away with their anti-science nonsense? Fact: There are gadgets that can be used to actually SEE the emissions of these greenhouse gases and these folks know about them...yet they tell their listeners that it isn't happening. I wonder why!