I am paranoid about germs based on past experience with colds and so I make it a point to use my right hand for external contact (e.g. door knobs, handshaking), and left hand for internal contact. And so if I eat food with my hands I use my left hand. If I drink from a glass I use my right hand, so as to avoid contamination from the server.
I rarely get sick now thankfully.
I guess utensils could have been touched but there is only so much you can do without looking too paranoid.
This guide does not apply to dating circumstances however 🙂