how do u tell if a rods going to be sensitive in the store or how does everyone get the feel of a rod

You can't really tell about sensitivity in the store, but you can check the weight, balance, and just how it feels in your hands.

If the store has a carpeted area you could run the tip across that to check the sensitivity.

when in the store ,very lightly tap the tip on something preferrably rubber , so you don't scatch a rod you haven't bought yet and also importantly , to check sensitivity . you should get a good idea of it by that