If it were me making the decision it would be because their identity is well hidden and people could potentially send large amounts of money to them at one time, sometimes with the expectation they will not get anything back from them for a long time (and may not check to make sure funds were received for days). This would potentially make it easy for them to straight up steal money from their customers.

While BFL was certainly a scam, they did not straight up steal in this way.

Fair point. Although they may have lost a good amount of money recently (this is speculation) as they had said they could potentially mix several hundred BTC though an exchange per day by depositing and then withdrawing from an exchange, and bitstamp recently disabled withdrawals unless your identity is verified. There were a few anon reports complaining about bitstamp not allowing withdrawals on unverified accounts (I always though this was them)
Another speculation would be that many users of illegal dark net sites will often use sites like bitcoin fog and bit mixer to obscure the source of their bitcoin when they deposit funds (or withdraw funds) from these sites. Although there are many other legit uses he may not want to advertise such a service so soon after receiving a subpoena for evidence in the Ulbright trial.

Theymos is probably concerned that the site may come under scrutiny as abetting crimes by mixing their Bitcoins. There is no dearth of bidders for ad slots so playing it safe makes sense.

Some casinos even have scam accusations out against them.

Does it matter? Its his forum and his liability, he's free to choose what he allows or doesn't in terms of advertising. He doesn't need a concrete reason.

Judging on Theymos original response, he doesn't want to disclose to the public why he doesn't want this particular service advertised. You can always send a message to him regarding the matter, but don't expect to get a response.

I would say this is probably correct. The lack of him knowing their identity (and the high chances that they use tor to connect to the forum) probably makes him less willing to allow them to advertise, as if they scam he could potentially be blamed and/or said that he is behind the scam.

This is a centralized forum. It is not realistic to have a decentralized forum. The closest thing to a decentralized forum is reddit and it is very easy to manipulate upvotting/downvoting

The casinos at least try to prevent people residing in places where gambling is illegal from gambling. It is not illegal to advertise a casino in places where gambling is illegal as long as the casino does not allow them to gamble

True, but people are also free to ask questions regarding the decision (whether theymos chooses to respond or not). I think denying bids is always going to raise intrigue and curiosity as to why, especially when the company doesn't appear to be doing anything wrong (that we know of) and there's much more questionable ads that get accepted without any problems. I'd personally like to know why they were rejected but theymos is under no obligation to provide any reasoning if he doesn't want to, like you say.

is this a discussion of legality or scammer ethics?  

whats legal in your country is not legal in mine.. ie all of these casinos.


ohh.  edit.  on the subject of scammer accusations and the like. not too many drug dealers go to the cops when they get robbed.

Bump. The least you can do theymos is reply..