Often by the time a cult starts doing harmful things, its members have made both real and emotional investments that turn out to be nothing but sunk costs. To avoid ever getting into such a situation, people come up with a lot of ways to attempt to identify cults based on nothing more than the non-harmful, best-foot-forward appearance that cults first try to project. If you see a group using "love bombing", for instance, the wise response is to be wary - not because making people feel love and self-esteem is inherently a bad thing, but because it's so easily and commonly twisted toward ulterior motives.