What I think is, we can't identify drugs by looking at photos, especially not pure chemical drugs (plants are different!) and I don't understand why people insist on thinking it's possible.
If someone else has had a bag which looks identical then it might have come from the same place and they could vouch for it having decent effects. That's very true. But, for example, I've had three different batches of aMT which, by looking at them, you'd think they were entirely different, yet they had the same effect. And just because it had decent effects for one person doesn't necessarily identify the drug.
Even people with a lot of experience with drugs find that the effects change, so they become unreliable. I have consumed dozens of grams of MXE over a few years, but if you gave me a 100mg of something that might be MXE I honestly couldn't be sure about reliably confirming it's identity even by taking it, because of my tolerance.
Does none of this apply to mephedrone? Seems unlikely that mephedrone is somehow special in this way.
It's a very full bag, and the bag itself is of nice enough quality :D