Some questions here are technical and therefore the answers are straight forward. However I can think of number of questions that are not technical, but rather based on quality of something. For example, can I ask about users' take on the extensive usage of a specific color(s) (e.g., blue) for a website? Or can I ask about the meaning behind a color for a domain of Web sites?
I don't see a problem with the sort of question you mention, however as it happens with any other one here on the site there are some things you should consider:
Add as much information as you can about your problem, explain why you tend to think one way or the other. Always try to add an image to better explain.
If you have a sample you are working on, you can also add it and turn your question into a critique question.
We have a lot of answers that could be read as subjective. As long as it is an informed answer, it is on-topic. The reasoning behind the text has to be explained, though. "I think black is good for a tech interface because..." and there goes the list of assumptions based on experience, research, etcetera.
If you are not sure whether your question is on topic or not, you can add it here and we can suggest changes if there are any necessary :)