I'm sure that some idiotic dealers do that. But generally, one uses lactose or cornstarch. Always spit in your palm, add a small sample, and mix. If it's grit

I'm sure that some idiotic dealers do that. But generally, one uses lactose or cornstarch. Always spit in your palm, add a small sample, and mix. If it's gritty or even cloudy, don't buy. If you intend to inject, also don't buy if it's viscous. And always do progressive dosage testing, to reduce the risk of overdose or outright poisoning.