Spices are some of the most under thought parts of BBQ.
What's in the Rub you use? Why? Is it helping or hurting?
I make all my own different Rubs because they are "variables" and I like to control as many variables in my cooking as possible. I keep them basic and can tell you what's in it and why and what it should taste like.
Go to yer spice cabnet one day with another cook and sit down. Pour each one of the main ones you use in little piles. Now one at a time taste what the Paprika tastes like. Think about the taste and describe it to each other. Find words that best describe that spice. Move on the the next and so on.
Take someone else's rub and pout it on the table and start seperating it to see what's in it. Some things you can see. Some you will have to taste for. Chef Paul taught me to do this. He's a MASTER but on a good day I can pour yer Rub in my hand and name you most of what's in it.
This is a big subject and should make for a good thread with the professional Rub makers and sellers we have around here.