For one, I think the federal government has better things to do with it's time then to read through every post on here, log everyone's names and trace their ip addresses. After sorting out those that arnt in the US, then using their addresses, open investigations on the local level. If they gather enough information to get a search warrent, putting it together and busting a person. Three months worth of investigation, paperwork, and red tape to stop a 43 year old man from growing 4 plants in his closet. Hardly seems worth it. Especially when several kilos of cocaine are being smuggled into the us as we speak. At least, I hope the government has better things to do with it's time.
On the other hand I don't think they would have even a second's worth of hesitation to bust you for those plants if the proper information presented itself. And it's fairly easy for that information to present itself. All it would take is one garbage man that notices something weird in your trash can, one phone call from a senior citizen neighbor that has nothing better to do with her time than to watch the neighbors and convict everyone of being a drug smuggler, or a random visit from the home owners association president that smells something funny. My concern is less with the federal people than it is with the local cops. Those of you that live in small towns know that their police have nothing to do most of the time than just drive around and give people a hard time. That's what I'm personally concerned about.
So I think the odds of getting caught from these posts are fairly small. However, I think the odds of me getting caught from my carbon scrubber breaking, and a neighbor smelling something funny before I notice much higher. But maybe I have it all wrong, who knows.
