Tren is hard to fake completely. Yes it could be underdosed but most of what I have sampled seems potent. You have the cough as a sign which ES mentions,
though not everyone gets it for some reason. I only get a metallic taste plus every now and then pain in my throat. Though I did get a low level cough that lasted all day long on one cycle, could have been the tren. I've injected my stuff on others and the coughing fits seem very annoying, guys pouring sweat and coughing like crazy almost panicking gasping for air

Then you have the mental effects, anxiety, slight paranoia, brutal nightmares, annoying night sweats. Llewellyn has said the Chinese raws may be like 98-99% pure but that's not something an end user is going to notice.