Does food taste better when you eat with your hands?

I would vote NO for that one.

Taste is based upon the direct interaction of your taste glands and the food you consume, thus using any kind of delivery (except one that changes the food itself) to those glands won't have anything to do with how good/bad the taste is.

However, there is the psychological aspect. Which is pure subjective, so one person can enjoy eating with his hands while another be totally disgusted by it.

I would actually vote maybe

for two reasons

1. just like amorphusion said there is a  psychological aspect which is pure  subjective.
2. and I agree with amorphusion about the glands , but I must add that using a metal object and inserting it into your mouth might add a metallic taste to the food ( it depends on the quality of your silverware ) , thus the food itself would change.

So he might enjoy getting a little dirty while he eats ( Sigmund Freud whould  have a lot to say about that ) or he just do not like the silverware taste.

I think so, for 3 reasons - 1 - in eating basically all the senses take place to create a satisfying sensorial experience, just like food taste better when it's served in a beautiful presentation, food would taste better when it create an enjoyable touch feeling whether in the mouth or in the hand. 2 - fruits and vegetables get oxidize from the touch of metal, and some of the nutritional value they have evapporate touching knife or forks (that's also why, to maintain the nutritional value of them while making a salad, it's better to cut it into big chunks) While bringing the fruits and vegetables straight into the mouth with the hand would keep them from loosing some of the nutritional value and flavor. 3 - Personly, when I eat with my hands, I'm less worried about keeping my manners and have more brain space to enjoy the food.