I heard that Taylor has strep throat. If so, it's no wonder he wasn't smiling.
If he had strep throat and still managed to sing, that, alone, is amazing. But it potentially could hurt him in the long run if he can't recover fully and quickly. The contestants have a lot of rehearsing and other things they do between the weekly performances. There's little time to rest and recuperate if you get sick. Both Tamyra Gray and Kelly Clarkson got sick during season one. Tamyra wound up being booted off the show that week, and Kelly has had a tendency ever since to get throat infections when she overworks her voice.
Last year, Bo's health problems began toward the end of the season and gradually got worse during the tour. It quite literally nearly killed him. Even though he got well, the lingering effects came close to ending his career before it really began.
Idol is as much an endurance test as it is a singing contest.