No zero balances, rich list and checking out the coin's own forum (if there are any) usually give a relative good base for a rough but relevant estimation.

Quality comments are not good for this kind of "measurement", as miners and other people who intend to dump and quit are also used to ask meaningful questions, and also used to make quality remarks, however they are not part of the community (or only for a short time).

Hero endorsements are not very accurate in these days .