Tribulus works by stimulating luetinizing hormone which then may stimulate testosterone production. Increased BO can come from increased hormones but can also come from more animal protiens. As tribulus does not contain any hormones it works for some people better than other and in some people not at all. It all depends on the induvidulas endocrine response. To get a full understanding of tribulus, look up tradtional texts on ayurvedic and chinese herbal medicine. Jade remedies by holms is a great book.
Remember that he4rbal medicines work best where there is an imbalance or deficiency to rectify.