The way I react to a Blockhead##### coming to my server, is I typically give them some special attention to make sure they know what's going on and what they're supposed to be doing. And even if their build sucks, I let it stay, until they leave of course.
But if they don't listen when I try to help and just start doing typical noob stuff, I'm the first to admit I'm likely to kick/ban. Never permaban though.
I like to take this sort of approach; reinforce them for things they build, no matter how good or bad it is. This will most likely make them want to build more. Some times I like to take away my own time just to help new players out with building, events, or just understanding parts of the game.
I've seen Blockhead's treated so badly some times that if I were them and I had just joined Blockland, I would probably just quit the game. I view Blockhead's as "on the fence"; meaning that they are influenced heavily when they first join Blockland, much like a first impression. They either get interested and have fun, or they get hated on and banned. I'd much rather them stay than leave.
I bet there have been thousands of people who bought the game, played for a few days, and then never touched it again simply because of their first take on the game.