Maybe it depends on the quality of the produce - I love the carrot and orange we get using the lovely juicy fresh carrots from the farmers market. Also he might want to reconsider the proportions of each.
I agree though that simple is best. Pineapple with about quarter of an inch of root ginger and one lime is delicious. Pineapple and orange is lovely. Orange and apple with a few white grapes is good. Keep everything in the fridge prior to juicing and drain into a cold glass to keep it cool and refreshing.