Is it possible that I can't detect 4-vinyl guaiacol (clove phenol?) Whenever I am at a tasting and others call a beer "clovey" I cannot detect it at all. I don't think it is a case of not being able to ID the aroma/flavor. Is this possible? I know that diacetyl is not detectable by everyone.
Phenols are fairly distinctive compounds and often have relatively low perception thresholds. It's more likely that the clove notes in your beer are subtle or are being masked by other things. In that case, it takes some practice to pick them out.
As others have said, experiment by getting some cloves and smelling them. Better yet, gently steep some of the cloves in hot water (ca. 170 *F for about 20 minutes) and determine if you can smell anything in the vapor. Once your "clove tea" cools down a bit, you can also taste it to get a sense of what the flavor is like. If you're feeling really brave, you can add it to beer and see if you can still detect the clove flavors and aromas.
Your interpretation of what you smell and taste might very well be different from other peoples' perceptions, but at least you will know what smell and taste YOU should be checking for when other people mention clove-like character.