Yes, you can easily over power the natural flavors and some flavors don't work well with others. Sweet and Savory work, Sweet and Hot work, Spicy works... but sweet and sweet, spicy and spicy, salty and salty don't work. The biggest failure I have had and many other is adding too many flavors that bring too much salt to the brine. IMHO when it comes to salt, use the bare minimum and watch the flavors and the amount of salt the contain. And for gods sake, leave the Liquid smoke on the shelf!
- Jason