Mind-altering drugs are still readily available in High Street shops despite a number of so-called "legal highs" being banned by the UK government.
The ban was introduced in December as a result of health fears.
But BBC Wales' X-Ray programme found goods like the Ecstasy-like pill Doves or the hallucinogenic herb salvia on sale as plant food or incense.
The British Medical Association's Dr Andrew Dearden said some retailers were trying to circumvent protective laws.
The ban on several "legal highs" came into force last December after a recommendation from the Advisory Council on the Misuse of Drugs.
Substances, including GBL and BZP, became Class C drugs, with a possible two-year jail sentence for possession.
However salvia, derived from the sage-like plant salvia divinorum and dubbed "the YouTube drug" as young people post internet videos of themselves smoking it and experiencing hallucinations, is openly on sale for use as incense or pot pourri.
And Doves, pills which experts say contain similar properties to Ecstasy, are packaged as plant food and advertised as encouraging "healthy growth and strong root development".
Neither substance is currently illegal under the Misuse of Drugs Act, although it is illegal to sell them for human consumption.
An undercover researcher for X-Ray was able to buy both substances over the counter in Wales at shops selling clothing and accessories marketed at young people - despite saying she wanted to take them at a party.
At Blue Banana's stores in Swansea and Cardiff, staff were happy to sell the researcher salvia, as well as a pipe to smoke it in.
At Rebel Rebel, an independent shop in Cardiff, the researcher was able to buy a packet of Doves even though the researcher made it clear she wanted them for a party.
Dr Dearden, chairman of the British Medical Association's Welsh GPs committee, told the programme that some High Street stores were trying to get around legislation that allows only licensed people to sell drugs for human consumption.
He said: "If someone is selling one of these things as a plant food but (saying) you can take it if you want to, or saying it's herbal, it's not a medicine, what they're trying to do is go around the Medicines Act, which is in place to protect the population.
"They're kind of saying we're not really interested in protecting you, we just really want your money. If these things are safe then then they should go through the Medicines Act."
Dr John P Thompson, clinical pharmacologist at the University Hospital of Wales, Cardiff, told X-Ray that Doves are in the same family of drugs as Ecstasy.
He said: "It's got a compound called butylone in it, which is related to Ecstasy. I would expect this to have the same properties, the same effect."
Dr Dearden added: "It's almost like a game of Russian roulette. The hope is you'll be okay. The risk is that you would suffer permanent damage and sometimes even death, and we have had people who've died from (Doves)."
A spokesman for Blue Banana said it was company policy to remain within the letter of the law, and that in accordance with last year's ban it had already stopped selling products which contain BZP and synthetic cannabinoids such as Spice.
The spokesman said: "Where it remains legal to sell items such as salvia for incense, etc, our policy has been... to train staff not to sell these items for human consumption.
"They must not enter into any discussion which would endorse this."
The spokesman said the retailer would review its policy to ensure that it was complying at all levels with the legal requirements.
Rebel Rebel declined to comment.
X-Ray, Monday, 1 February, BBC One Wales, 1930 GMT.