The best way to avoid misunderstandings about the terms of an invitation is to be clear about them up front. And the more unusual the terms, the more important it is to be direct. No host has ever asked me to pay for all the food and drink during my visit, as you and your husband envision. And I have never expected that from any houseguest. Your own experience belies your assumption that guests will “gladly” cover these costs. They don’t!