I usually try to find games where there are lots of noobs. TDM is one of them. When I see the other side getting close to 1:1 ratio across the board, then I know I'm not getting a Bloodthirsty there. I'll then switch to another weapon to level up, finish out the game, and then find another game.
MW3 (Wii): GI-Jew Monster Hunter Tri (Wii): John (US Server)