I Personaly wouldn't know what your talking about since I've never encounter a pill with acid/speed/ or heroin in it. That is MOSTLY a myth. Speed I could see cause it's cheap. Acid I doubt because you would have to cook it down to a crystal form inorder to press it into the pill. It would be easier to take liquid or blotter with your pill. And heroin is far to expensive to be smashing into pills.
Most X is made up of MDMA, MDA (a byproduct of MDMA), MDE derived from MDA, MDB and MDEA. All of these substances create a different effect and give the user the impression the pills are "dirty".
If your having a clenching issue while on MDMA it's because you have a magnesium deficiency id get that taken care of before I took any more X.
To the thread starter your X was bunk.