These affiliates do not seem to understand the gravity of false promotions like these.
This is not some amusing little game of deception... it is a matter ultimately involving punters' financial choices and therefore demands integrity and respect for those on whom it is targeted.
I'm sure they do understand it
However, what they also understand is, when they do it, if all a casino is going to do is 'tell them off' then the risk is worth it, as they will be making loads of money from it.
What should happen is in my view, for straightforward spam, when requested, the affiliate should be able to show a legitimate proof of opt in (by legitimate I mean something with the customer IP attached and a URL from where the opt in form is hosted at least). If they can't, then, for a first offence, all earnings for that month be confiscated, and any new customers detagged for the same period. The link should also be 404'd.
A second offence should be the same, but for a 6 month period.
A third should be instant termination of the account.
I'm actually being a bit generous there, but does allow for any mistakes to be corrected in case the rules aren't fully understood.
For things like we have seen in this thread though, fake adverts, lies, no WORKING unsubscribe link, any spam that doesn't comply with the laws in the country to which it was sent, or the casino / affiliate is operating (ie UK would be UKGC, ASA, ICO) then the account should be terminated immediately in most cases.
Most of the above is already covered in affiliate agreements anyway, just not enforced, and anything not could be added to the terms & conditions quite easily.
Spam will never stop completely, but if an affiliate knows he is likely to not get paid for any spamming he does, there won't be any point in him doing it. Legitimate affiliates will have nothing to fear.