While on my last day on an internship last summer, I heard on the morning call a UK rates trader say something along the lines of: "Most of the curve is at fair value at the moment, so nothing particularly interesting in the way of trade opportunities".
How do traders determine that the curve is at fair value? Is there a general approach to doing this? Or do traders develop their own models for determining it? Can traders disagree on whether or not a curve is at fair value?
What are some good places to learn about determining this?