I think not all cases will fit mainly into those two reasons because primarily, there are a lot of contributing factors to consider why a coin dumps its price after getting listed into an exchange. You have got the point that maybe that coin has no real value that is why the price dumps right after getting into an exchange but some coins experience dump because of the case with regards to the popularity when it is being promoted or advertised. Maybe, it has not reach into a big group of people to know about the coin due to the fact that there are already lots of existing coins within the market so it is hard to see and define which are the new ones that deserve to be purchased to raise the volume when it comes to demand to rise up the price value of a certain coin listed on an exchange. The problem on publicizing the coin will be a great challenge for the creators to let other people know about the coin to gain demands to be able to make the price rise because even if a coin is really that good, if the crowd doesn't know about it, and there is no demand for it, the price will really go down once it has already done the listing process for an exchange. So the strategy on promoting the coin will be a great key to gain attention which will brought up demands that will make the price value rise.