I don't really think you can legitimately take revenge on them or sabotage the site in any manner. Plus they will keep on building these sites, with or without

I don't really think you can legitimately take revenge on them or sabotage the site in any manner. Plus they will keep on building these sites, with or without you. If you are lucky, there may be some procedure in your country for reporting them. Really all you should do is just write them a letter stating that you feel you can no longer work for them and you disagree with their business practices. Something professional and polite. Once you have made your position clear and walked away there should be no reason for them to bother you afterwards. If they do you should just ignore their emails/calls. Can you really spot people like this in the future? As you've stated above, there were some suspicions but nothing concrete and you did your research and found nothing. Did you look up their names as well as their company name? Often or not they'll just start a new company when one gets a bad name but you might find mention of their names with previous ... activities. They lied about their original intent, perhaps they knew you'd get cold feet if you knew their business plan. So perhaps they'll not be surprised when you stop working for them.