I didnt read all the responses, but I dont think the authors commentary about everyone saying that Jims stuff is good is really how it all goes down at all. People are not making reports on dealers, they are making reports on products and these products often have their own ways of identifying them and its NOT just about the rep of a human being but the ability to recognize the appearance of a product and to learn about any bad stuff going around and hoping to help identify some of it....its never 100% safe, and a bad product can look identical to a good product, but this is about harm reduction and any info you can get on dangerous batches can only help to reduce harm.
And getting warnings about bad ideas, like poor combinations is a really good resource to have. If the only advice they ever hear is "just dont do it", they may listen or they may not. If they dont listen to "just dont do it" then its better if they listen to "well, dont mix this and this at the same time or your heart will stop, but go ahead and take this with this and do those two seperate"....no, its not what many parents would find ideal, but its better than people having no guidance at all and end up killing themselves because harm reduction was not provided to them.