I'm a prolific plunderer. I've had my Blue Badge for what seems like forever, in 2 worlds. I've 23K wins in K world; so let's guesstimate some 18K-20K plunders there; and in T I'm 10K wins, for approximately 7K-9K plunders.
I warn people both directly, and in my city description, that I will plunder them. I'm relentless. However, as I Age up, and the hoods are filled w players who have made bad decisions (tech tree racing, off cycle collections, etc.) I'm starting to feel differently about taking their stuff. Granted, if they leave fps laying around, those are mine. But if it's just some regular stuff, I'm tending now to just leave them be. Their entire value to me now, asides from tower points, is their GBs. I'm more concerned/vigilant about sniping the hoodies, or, just locking spots on their stuff, as my K world Arc is 85 now. So even 1.9 donations are productive, tho the fps are a wash on anything under 1000 invested.
When this discussion was raised in Big Bang, some guildies called it "stealing" which I resented. The mechanism is there for a reason, and I always play within the rules (unlike Septic in T world) and felt that my guildies were being to harsh. But since that discussion, I tend to see some of their point.
Which leads me to think that, perhaps, plundering of some low end hoodies city is effectively harming the future of FoE, as I see a number of mid level players abandoning their cities.