I agree that there are a lot of factors which influence the quality of fruit and veggies, and that they are not causally related to whether the vegetables are organic. However, I am convinced that there is some correlation. For example, I expect that it would be difficult to sell unripe mass produced tomatoes as organic.

One objective thing I have noticed is the quality of milk. I have an Aeroccino-machine for frothing milk. When I use milk from Whole Foods (an expensive all-organic food store), it consistently creates a great foam, whereas if I use non-organic milk from a normal supermarket, it usually completely fails. It would be great if someone else who owns an Aeroccino machine could try to replicate this claim at home..

I expect that there is a simple explanation that has nothing to do with pesticides, for example that Whole Foods has a better logistics system that keeps the milk properly refrigerated at all times. However, my point is only that many customers will note that the organic milk from Wholefoods foams, whereas the non-organic doesn't.