Hey I just lost 3 games in a row, accidentally in every one of them 2 ppl were taking mid or going bot. 1.st game: The person was laughing at me after pleading for only 1 mid, arguing there's no mid on dominion. Even after pinging on mid point and explaining it to him. Of course that one was helping Tarric to take mid. 2nd game: Karthus with Smite taking mid with partner. 3rd game: Caitlyn who asked while waiting in the base is she ap or ad champ. She went bot with other player.
I'm gonna take a break now and work on my approach a little and try to see those people as visionaries, not as complete noobs n' trolls who are comming to Dominion just to tryout new champs and practice their jungling skills.
If someone is trying something you see as odd, ask them about it! If they have an idea in mind they may be willing to share it to hear others thoughts on the matter. There may not be time in the match for it due to Dom's pace, but there is post game chat and friend requesting as well. If they don't know what they are doing, or don't respond when you ask, give them some direction with helpful, non-spammy pings, and places you think they will be most helpful at.