Not all aliens do that anal probe thing. Only the ones from the Err Tao Section. It's rather embarrassing but they don't do it for research at all. That's just a ruse. They are collecting human intestinal flora as a food additive. The word is among the illuminati is that it is a very high priced item in the fat shops of planet Ukku and Zunda'ho. It's helped by rumors that it is supposedly a great help to one's third sex life. No one is proud to be part of the trade, but money talks and everyone warps out.
This was something you needed to know.