what does "sizing things up"mean？
That was the only confusion. The aides made everything easy. For ten minutes they had been mingling among the guests, sizing things up, and they blended so gracefully into the social tableau that it was difficult to believe that their campaign ribbons were authentic. Was it true that Ted Clifton (Maj. Gen., USA) had commanded a battalion at Anzio? He was something out of D'Oyly Carte. Had Taz Shepard (Capt., USN) really won a Navy Cross for extraordinary heroism in the Solomons? His face was as seamless as a midshipman's. And Godfrey McHugh was the unlikeliest of all. He didn't even sound like an American. Raised in Paris by a Dun & Bradstreet father, Brigadier General Godfrey McHugh (USAF), better known as God, spoke English with a pronounced French accent.