The Steamwheedle, while on good terms with the Alliance, definitely seem to be on slightly better terms with the Horde, if only because they have far more contracts with them than the Alliance. They can be described as "a little bit crazy, fairly greedy and opportunistic, but generally friendly as well".
The Bilgewater joined the Horde after SI:7 tried to kill them as witnesses to their attempt to kidnap Thrall. Their loyalty to Garrosh seems to be a combination of fear and just being along for the ride. While they possess all those same characteristics as the Steamwheedle, they seem to place a little more emphasis on being crazy (explosions & wacky inventions) and a little less emphasis on being greedy (relatively speaking compared to other goblins, anyways).
The Venture Co., as one Tauren put it, are loyal only to greed. They are evil and will do virtually anything to turn a profit. Say what you will about the other two cartels, they do have their limits as to how far they will go to turn a buck, either that or they have enough foresight to see that stabbing people in the back causes you problems in the long run. Oddly enough, you don't see nearly as many explosives or wacky inventions around the Venture Co. as you do the other two cartels.
Didn't show any real fondness of explosives.
Was willing to hire South Sea Pirates to attack his own people... twice.
Was willing to rob the food stores for himself, leaving everyone else to starve.
Was willing to enslave his own people.
He definitely sounds more like Venture Co. material than Bilgewater or Steamwheedle. It's not like it would come as any great surprise to anyone if he betrayed them... again.