Answer:
How can a pants pocket be empty and still have something in it?
Timid or weak people are said to not have these.
Bobby likes Jimmy but not Joe, apples but not pears, jeeps but not vans, shinny but not hockey, tennis but not squash. Who will he like, Sara or Sally?
The more you look at it, The less you see.
I'm often served as a "rack of ..." I'm often smoked or grilled, with bones in, and slathered in BBQ sauce.
All about, but cannot be seen, Can be captured, cannot be held, No throat, but can be heard. Who am I?