The game "Caravan" in Fallout: New Vegas is to easy and can be easily abused. I am not going into how to play but I never lose. My deck for caravan consists of 2s, 4s, 6s, 8s, 9s, 10s, Js, and Ks, nothing else. I don't even know what the queen or jokers do, that explains my expertise in the card game. I find myself never losing though. I use mostly even numbers to get to 26 with a lot of kings to double my points and if the NPCs get any ideas, I know how to use my jacks. Here is how the game can easily be abused, I abused the game on Lacey in the Mojave outpost. I talked to Lacey and went into her shop and noticed she had 7000 caps to barter with. I had no idea normal stores could have that much money so I decided to get some caps by playing Caravan. So the max ante that showed up was 2000 so caps and I matched that and I won, played again and the max was 1800 or so caps and I won again. I kept doing this till she had a measly 500 caps and I had around 23000. What I did next is what abuses Caravan. Lacey owns a shop. I took all my money, and bought everything. Then I saw she had around 5000 caps to barter with again and I played Caravan again without losing till she had no money or items left. I had my 23000 caps back and all the items in her store. This can be repeated with all stores that play Caravan. You can get all their items and money for free and then play for a day or two and return and do it again. Giving you as much ammo, money, stimpacks, armor, crafting materials, etc etc etc as you will ever need. I reloaded to before I did this knowing it would kill the game for me.
I believe Bethesda should figure a way to max the amount of caps you can get from an NPC or lower how much they can ante every day or figure some other idea, maybe increase the difficulty level of Caravan depending on your Win/Loss record. I lost 3 times in the beginning of the game to learn how to play and never have lost since. I no longer really play Caravan anymore unless I ante maybe 1 cap just to play the game.
tl:dr : You can abuse the game Caravan and rip off everything an NPC owns if you know how to play giving you anything you really would want by playing until you get all there money, buying everything in their shop and playing again to get all the money you just spent. I think this should be fixed.