If you trade on broker dealing desk, hence your order will not be forwarded to the interbank market, but still, hold on the desk broker, if you win or getting profit hence your broker will lose, but if you loss hence your broker will win, so broker dealing desk usually will make you losing money, although they offer big bonus etc
ECN broker is the non-dealing desk, and they will forward your order directly to interbank market, and this is better than dealing desk broker.