Note: The below argument only applies to clearly and accurately labled branded products, not to branded products like some of the above mentioned where you dont know what is in them....if you dont know what is in them, its best to steer clear and go with the pure substances....however, consider the following.
There are two area's of harm reduction.....the harm that is caused by the drug, and the harm that is caused by police if you are found with the drug. Generally, the later causes even more harm than the former, though the former also causes significant harm.
There is a problem with branded products when the ingredients are not labled, but sometimes they are in fact labeled.
Buying a pure substance in a suspicious looking bag of white crystal does NOT actually mean that you know what you are getting. There are plenty of companies, based on reviews I have read, that send mislabeled substances in suspicious looking baggies.
There are 2 additional drawbacks to buying the pure substances.....1)It just LOOKS like street drugs. The fact that it looks like drugs, to an untrained eye who has not tested it yet, means there is a higher chance of it getting field tested. While it would not protect you necessarily if caught, there is a lower chance of being investigated if at a casual glance it looks innocent enough.
The other concern is that with pure substances, you can end up with something like MDPV or Naphyrone.....if you think you are getting Mephedrone, Methylone or Flephedrone but you were actually sent mislabeled MDPV you could die. The pure substance would have radically different dosage and maybe kill you. The reports I see are really really scary....people ordering an RC and getting a completely different RC in a baggie. At least a mixed product was tested and designed for the end user.....maybe not by a genius or chemist, but by somebody who found a mixture they liked or thought people would like, using an eyeballed dosage that is less likely to overdose you if you do cocaine sized lines.
For those two reasons, I think that branded products that list all the ingredients on their website but not on the innocent looking product have some things going for it.....but its a bigger concern if you live in the US compared to the UK, since the US has the analog act and more domestic spying, so you have more reason to make your package look innocent compared to the UK. Getting a bag of white crystal in a bag looks like somebody sent you a bag of methamphetamine, which leads to a field test, which might show up as a false positive....later you might be found innocent, but its a scary situation to be in. It can bring the police to your house, and its potentially downhill from there. A bag of bath salt might be something the DEA is aware of, but its more likely to get ignored, especially when its neatly sealed in a professional looking product, compared to just a mini-ziplock of white powder.
Bottom line is, know your sources, test your samples, and be aware of real unbiased customer reviews.
Harm reduction requires sites like this, but it also requires sites that allow source talking and sites that allow methods of passing drug tests, since for many people the harm of prison is worse than the harm of some recreational drug use.
On average though, I think its better to be dealing with pure substances, unless they are ridiculously potent like MDPV, though I suppose its cost effective pure.
If you dont know what is in a product, then obviously its a really bad idea to take it.....there are many many branded products that do not list the ingredients truthfully or completely....My above argument does not apply to them, only to clearly and honestly labeled branded products.