Well, I will have a trading bias based on current analysis. Often times I will say I'm not taking any long trades because the trend is down.
As far as personally liking to trade only long or short..... No.
You figure that, in currency trading, you are always taking one side long and the other side short. (If you go long Eur/Usd, you are going long Euro and short Dollars) It's not like in Stocks where you may actually have a bias to only go long.