By "watered down" I mean Bibles that are paraphrased which leaves the translation open to the interpretation of the writer. Of course, paraphrased Bibles are not all bad. For example, a child that can not read well, may benefit from reading a simplified paraphrased Bible until their reading level goes up. I would see this as the equivalent of parents reading to their children Bible stories which are also paraphrased from the Bible, but even these one must be be careful because I have found big mistakes in children's Bible stories. So, when it comes to seriously studying the Bible it is good to use a more accurately translated Bible than one just in story book form. Also, people who are given a Gideon's Bible often have no idea that there are paraphrased versions out there so I think it is nice to give a good translation to start off with.
As for "liberal" I mean translations like the "Contemporary English Version" which uses gender neutral words, and makes actual changes in the Bible to fit in with society's thinking rather than what God actually said.
Another thing I should have noted is the Gideon Bible does not give Bibles that a denominationally geared. For example, New American Bible has notes to favor Catholics. I know there are some Charismatic Bibles out there as well, and I am sure lots of other denominations have Bibles to support their denominational teachings. But the Gideons seem to stay away from that. They just support the Bible and let the Bible speak for itself, and then let the person choose their denomination based on what they read directly from the Bible. I respect the Gideons for choosing a translation like this rather than a translation that is supporting a denomination.