Suppose I asked a question about graphs; do I always have to precisely define, what kind of graph I mean (directed/undirected, with/without parallel edges, with/without loops, connected or not, with isolated vertices or not), but from the question it could be concluded what kind of graph I "have in mind". Would that justify a downvote or can I hope that people either can also know what kind of graph is meant or point out the defect in a constructive comment?
Just to make things clear: my experience is that the people at MO are very kind and try to help, but in rare cases an unconstructive comment or even an uncommented downvote are possible.
This question is rather aimed at a guideline for downvoting or negative comments and not at critizising the reaction to specific questions.