Eugenol is often detected in beverages that have been aged in oak. Euginol imparts a spicy aroma of cloves or allspice. Especially in beer, if eugenol levels are noticeably high this is indicative of a flaw. In this case microbial contamination is most likely to blame. (Wine,Beer,Spirits,Sake,Mead/Tasting Terms Chemistry & Flaws)