This would be a sign for me, reflecting lack of context and enough prior self-attempt. Due to this impression, these questions usually receive less attention. The best strategy (in my opinion) is to leave a comment asking for further improvements or adding more context to the question, to make sure the OP cares enough about what s/he has written.
However, I don't think new users realize at the beginning that they should actually improve their question. Most often, the updates remain as a comment or two. Unfortunately, the process of getting familiar with the site (and how it works in general, including responding to the answers) is a slow and gradual one and new users don't know much initially. I also realized, some of the new users of dsp.SE are unregistered, which again causes this group of users being less responsible about their post (haven't seen this in Math.SE). Most of the questions are asked by new users. That's why there are several questions of this type.
In case of no response, I think the usual approach is to put the question on hold.