I find this enormously interesting since I just finished alot of research for a major paper I'm writing on cults. One thing that sticks in my head was something I read - "One Man's Cult is Another Man's Religion". Another point was made that many sects that started out as cults have become mainstream religions.
That kind of attitude towards cults should only apply when using a "looser" definition of the word. Sometimes people call a religion a cult merely because it is new, strange, or not mainstream. There's really nothing wrong with that type of cult.
What most people think of when talking about cults is the destructive types that use various forms of control to remove individuality from its members, use deception when recruiting, etc.