breedingroom,
First off I am not saying you are wrong, I agree with you 100% that it is obscene that many LFS do not give warnings. When I worked at the LFS a while back, I did and so did my co-workers. We did our best to find out about the customer, tank, system, age, etc... before we would recommend anything.
At the time I did not know about the severity of toxin in zoo's but I would always explain to customers that everything in a salt tank should be handled with extreme caution, especially due to the "unknown" factor we all deal with. I have had numerous encounters with unknown bites / stings that have sent me to bed early, and I share those experiences to stress the possible dangers. (Or the time my anemone decided to grab me, and I had to sit there for 45 mins while he decided if my hand was edible.

My hand was swollen for at least a week)
I wish there was a way of implementing a mandatory warning system, but quite honestly, it would probably be in the form of a sign that collects dust in the front of the store. Or, they can ban zooââ"šÂ¬Ã¢"žÂ¢s only to find that many other creatures in our tanks have toxins and ban those too. The best option imo is to stress the importance for consumers to research what they want to buy (or at the very least, research what they DID buy.)
BTW: Many, Many places do sell toxic items, take wild oats (natural health store) and the herb section, WOW!, and those products are actually sold for ingestion purposes.
Just my $0.02