Many Americans are living out of the country and can vote by absentee ballot in elections, so they deserve to be campaigned at.  I can't see the advantage to campaigning to these people, and of course, it shouldn't be on an "official" visit paid by taxpayers, but they are voters and should have to put up with the embarrassment the same as the rest of us.  What people in other countries make of our incessant politicking I can't say, but I bet it is not flattering.