I say, make them want to. We all start out thinking we're doing this with good people who will always agree with each other, therefore strict guidelines aren't needed. That's only true for a short period of time.
People change, and so does the membership.
After five or ten years you'll find you're living with a very different group, and the only commonalities are what was put in the bylaws ahead of time that caused the group to be self-selecting. My group is still in the formation stages, but we realized early on that we needed guidelines in our bylaws and in the association contracts that everybody signs that have reasons for kicking people out. Also it's important for people's peace of mind to know that there are clear, not random, reasons for being removed. We'll not be running for a while, but seeing this thread I'm glad we thought ahead about this. Hopefully it'll help avoid the things you're seeing.