I think admin. cares very much and does a great job in removing anyone who has proven themselves to be a dishonest or unreliable person with which to trade. And this, even though it is not really their "job" to "police" people advertising within the forum. It is very much a "buyer beware" situation, until someone actually PROVES themselves to be untrustworthy. If even knowledgeable people within the worldwide mantis circuit do not even know, or have any recommendations (good or bad) about a particular person, then how is admin. to know? You wouldn't want admin. deleting people suspected of being untrustworthy, but not proven so. New sellers or traders, previously unknown, with no feedback are a risk. But does that automatically mean they are bad? You can't just delete people who are "suspect" without good cause.
Another forum member PM'd me just a bit ago asking about the risk of making a prospective trade with a person in the Classifieds section. This is what I told him:
NO. I have emailed him asking for references. He replied that he would send some, but never has. He also made a trade offer to me for 1 Idolomantis, 2 Gongy, and 1 Bleph ooths for 4 P. chlorophaea ooths. Yes, the P. chlorophaea are an interesting species... but what he's "offering" is potentially worth much more than what his proposed trade is. It's too good to be true.
Always remember... if it sounds too good to be true, it probably is. Of course not every great deal is a scam. There are genuinely nice people who are generous with their trades and such. But usually those people are well known on this forum, and others, all around the world. Considering his advertisment was his first and only post, no one really knows him or has any information about the validity of previous sales/trades, his offers sound too good to be true, he has obviously and blatently stolen others' pictures to advertise his supposed species (which means he probably doesn't have any of the species he claims), and the fact that he's from Poland (Kruszakus told me Poland is rife with scammers) and currenly living in Japan... or so he says....... put together, it all screams SCAMMER!!!!!! I think he is trying to get people to agree to trades and rake in a bunch of free ooths to then turn around and sell. I sincerely advise you not to send him anything, or deal with him in any way.
Edit: Forgot to answer your question! No, I don't think I've ever been intentionally scammed by anyone on this forum. I have had some disappointing trades, buying ooths that never hatched. But I don't believe the sellers intentionally sold ooths they KNEW wouldn't hatch.