What this thread has made clear is that what the airline will do and immigration will do are variable, depending on the route, airline, country, moods of the officers involved, etc. Let me just add to our shared experiences by saying what actually happened yesterday when I flew from Seoul to BKK on Korean Air. I checked in online, then went to the airport. At the airport, the carrier checked my passport and boarding pass them made me tag my own bags at a kiosk. Of course, I needed to show the boarding pass and passport at security and at the gate, but that was it - no ongoing ticket or length of stay questions. At immigration in BKK they wanted to see the boarding pass that I had just used, asked me how long I'd stay and wanted to see my accommodation confirmation. So I wasted $12, but it was well worth the peace of mind.