Maybe it is just me, but after exclusively eating organic food for a while I can tell the difference in taste. The other stuff that is grown using pesticides and synthetic fertilizer is not tasty like organic food is. This is why we get organic delivery right to our house now. I am spoiled by the better tasting foods. My wife had been eating some organics and some of the regularly grown fruits and vegetables. Then she switched to all organic about a month ago. I bought a regular non-organic banana at the cafeteria at work and slipped it in with the other bananas we had at home. She ate it and told me it tasted funny. She suggested there was something wrong with our organic bananas. I told her what I did, and that it was to prove you can tell a difference.
I do not think you notice it much if you are eating a mix of organic and non-organic food. It is sort of like people who drink soda who switch from sugared sodas to diet soda. You have to do it over time because diet soda tastes different. Then if you get a sugared soda after exclusively going diet, you think it tastes gross. The thing here is that organic foods may have a health benefit that goes beyond the good nutrition factor of just getting better nutrients from fresh fruits and vegetables. Organically grown things can impart less chemicals into your body that you do not want.
Over time I believe this can make a huge difference in our health. This is why we eat organically here. It is not about how we are doing right now today, but it is about how we will be doing as the years go on by. Eating healthier food has to have a net positive benefit. It just makes good sense.