I was reading a report that said 25% of otc supplements have something in them that isn't on the label. The most frequent product not found on the label of test boosters was Vi agra. This in a sense is very smart because most men would think their testosterone levels are going up if they get stronger erections and more frequent erections. If I can find the article again I'll link it.
Also if you guys take these in PCT keep in mind they don't really work. The only proven ingredient other than actual testosterone itself, is D-Aspartic Acid (DAA). Even though DAA increases test production slightly, it only increases on average by about 30%. However, the study also found a 30% increase in estrogen as well. Either way a 30% increase won't significantly help you gain more muscle.
Hope this helped. And dont buy into that Tribulus and long jack shit.