My answer: I don’t think there’s any rule about combining spices, however, if I’m not familiar with a spice, I approach it with caution.
To beginning cooks and bakers, I’d suggest following recipes until they become accustomed to the different spices and herbs. For those of us who are more experienced, I’d suggest researching the spice before jumping in. You can also combine a small out of the spices in a small dish and then sniff its bouquet several times throughout the day. Our nose is the best tester to know if something will be good to eat, or not. I’d also follow the old entertaining rule to not try out a new recipe on company (in this case unfamiliar spice combos).
I put Google to work in research of why we don’t sprinkle cinnamon on our pork chops. I was surprised to come up with what looks like a scrumptious recipe for Cinnamon-Spiced Pork and Plums which tells me just about anything goes these days when it comes to combining spices, herbs and flavors (bacon ice cream comes to mind). I have an Aunt, who is a terrific down-home style cook that has for years put a dash of cinnamon in her spaghetti sauce…and it’s good.
Here are a couple of links that offer suggestions for using spices and herbs that might be helpful: A Guide for Using Spices and the Food Network. Thank you for your question, and good luck, Pegg! Let me know at firstname.lastname@example.org if you come up with any exotic combinations of spices and herbs Country Cook readers might like to try.