I've found that comments have a restriction for minimum comment length. I.e. it's impossible to post too short comments.
Yet in the same time this can be overcome with using formatting. For example, simple
Question fail comment is too short while
_Question fail_ is not (added 2 symbols - actual length increased while comment have same content when it is displayed).
Is it a bug? Should comment length be counted without paying attention to formatting? (since we're able to show them properly, why do not count real, meaningful comment length - note, this has nothing to do with other special characters, like single
_ or similar, only formatting)