How would one recognise if a Buddhist group is a cult? How would one recognise if a sangha or Buddhist group is a cult or has cult type tendencies. Are there well established things to look out for? Are there cult type behaviours or patterns that would be particularly linked with Buddhism or are all cults broadly similar irrespective of their religious inspiration? 

We have tried to answer questions about cults before here and here however these questions have been closed down as too opinion based. However I'm hoping by broadening the scope and moving it away from any one group it may help to keep this more objective. Also I would imagine that there are scholarly studies in this area so I'm hoping that this will also assist in objectivity.

As a side note I'm aware that the term cult is a controversial and emotionally weighted term. It's difficult to get a good definition but I found one here that seems reasonable


  A group or movement is theologically a cult if it identifies itself as
  belonging to a mainstream, recognized religion — and yet rejects or
  otherwise violates one or more of the central, essential teachings of
  that religion.


however I welcome any other definitions too.
Some answers from the suttas (emphasis mine):


  Here, monks, a monk might speak like this: 'In a certain dwelling place live many elders, very learned, who have learned the traditions, who are bearers of the Teaching, bearers of the Discipline, bearers of the Tabulation, I have heard this directly from those elders, directly I learned it: "This is the Teaching, this is the Discipline, this is the Teacher’s Dispensation."' Those monks’ speech, monks, is not to be rejoiced over, not to be scorned at. Without having rejoiced over it, without having scorned it, after learning those words and syllables well, they should be laid alongside the Discourses, they should be compared with the Discipline.
  
  If, when these are laid alongside the Discourses, compared with the Discipline, they do not fit in with the Discourses, they do not compare well with the Discipline, you may here come to this conclusion: 'Certainly this is not the Gracious One’s word, it is not well learned by those elders,' and, monks, you should abandon it. If when these are laid alongside the Discourses, compared with the Discipline they do fit in with the Discourses, they do compare well with the Discipline, you may here come to this conclusion: 'Certainly this is the Gracious One’s word, it is well-learned by those elders.' This, monks, is the third Great Referral you should bear in mind.
  
  -- Mahāparinibbāna sutta, DN 16


and:


  [...] "What is the cause, lord, what is the reason, why before there were fewer training rules and yet more monks established in final gnosis, whereas now there are more training rules and yet fewer monks established in final gnosis?"  
  
  "That's the way it is, Kassapa. When beings are degenerating and the true Dhamma is disappearing, there are more training rules and yet fewer monks established in final gnosis. There is no disappearance of the true Dhamma as long as a counterfeit of the true Dhamma has not arisen in the world, but there is the disappearance of the true Dhamma when a counterfeit of the true Dhamma has arisen in the world. Just as there is no disappearance of gold as long as a counterfeit of gold has not arisen in the world, but there is the disappearance of gold when a counterfeit of gold has arisen in the world, in the same way there is no disappearance of the true Dhamma as long as a counterfeit of the true Dhamma has not arisen in the world, but there is the disappearance of the true Dhamma when a counterfeit of the true Dhamma has arisen in the world. [...]  
  
  "These five downward-leading qualities tend to the confusion and disappearance of the true Dhamma. Which five? There is the case where the monks, nuns, male lay followers, &amp; female lay followers live without respect, without deference, for the Teacher. They live without respect, without deference, for the Dhamma... for the Sangha... for the Training... for concentration. These are the five downward-leading qualities that tend to the confusion and disappearance of the true Dhamma.
  
  -- SN 16.13