Originally Posted by CDTraveler

Oil, especially olive oil, can really change how some flavors are perceived. The oil can be so cloying that you don't actually taste the season unless it is extreme.

Other things to consider are how fresh the spice is, is it finely ground or coarse texture, whole leaf, etc. For example, oregano fresh from my garden has a much "sharper" taste than the leaves I dry to use over the winter. Have you considered getting a book on spices, which might suggest the optimal ways to taste them?