I don't know how long you have been in this industry...
Depends on what you mean by "this industry" (there, back at you ;)
I'm not an online advertiser, have never used Adwords (probably should just for the edification) or for that matter, banner exchanges, link exchanges (well link exchanges based on actual industry relationships yes but not link exchange services), etc. I don't purchase traffic or really use many of the standard Internet mechanisms for attracting visitors and I've certainly not engaged in arbitrage. Can't talk about my "niche(s)" but I'll say that I build things from the ground up and that starts with personal or business relationships and progresses to word of mouth and other forms of referrals, traditional marketing when appropriate, and yes, I know how to take an established site and lend some of it's reputation to a new one when it makes sense to do so. It's definitely not the get-rich-quick approach but it provides for fairly steady and consistent growth. And just to be clear, not everything I do has an Adsense motive attached to it. Some projects are about moving widgets for a client or even just for fun. I also do pro bono stuff around the community from time to time.
and they won't pay much attention to collateral damage
Which is why (we)b publishers in the Adsense program really are all in the same boat. Doesn't matter who tipped the boat over once it starts sinking but I get your point that throwing the troublemakers overboard before that happens is a sensible solution. So being on the sensible side of the boat is a good strategy but there are still no guaranties.
Anyway, it's been a long but productive day and I've got just enough energy left to say, have a great weekend all. So,