I think that when the same thing keeps on happening over and over and over again, it is helpful to look inward instead of developing conspiracy theories. On every new site you join, you agree to the terms of service, and you get to start fresh as a new person. Are you not following the rules? Are you being aggressive or hostile? The only common denominator in all of this is you, so I think its time to seriously look at your behavior. (You can't use the internet as a common denominator because its so vast and varied---that would be like saying all Americans are a common denominator.)