Exactly. Even with the shittiest coke I've ever had, the drip of it down my throat definitely made it go numb. Basically, any of those -caine drugs will cause numbing, so it's not really a good way to judge. IME, a sign of good coke is that it doesn't sting, burn, or hurt when snorted, but I'm sure this is a YMMV situation, especially since, cocaine is stepped on and cut to shit regardless of how "good" it is.