If you DON'T expect your E to be laced with any of the following: PCP, heroin, probably meth somehow, fertilizer, napalm, industrial by-products, meat by-products, semen and sometimes vanilla, then you don't take the stuff!
No that stuff is so crazy because you never know what you're getting. Sometimes you can tell by eyeballing it, but that's still not always fool proof. Like for instance, you know it has a shit-ton of heroin if you can see a lot of brown blotches and flakes. Almost ALL E has a certain amount of heroin in it, it's nearly impossible to get pure MDMA, I'm actually sure it's in powder form if you do if I'm remembering right.
I've personally never touched the stuff, but I will say people are pretty hilarious when they're on it and they start touching your face and petting your hair. Doesn't seem like it would be a substance to my preferences, so I never bothered.