This meta question was inspired by a recent site question (https://crafts.stackexchange.com/q/78/30) but I believe it may be likely to come up relatively often.
Arts & Crafts can be a moderately subjective topic. Subjective content isn't necessarily bad for our site, but there's often a wide gray area of "opinion-based" that may be worth discussing, and delineating policies. Sometimes the artist prefers a particular tool or style because of how they use it (I find that smudging is easier with This instead of That), sometimes the decision comes down simply to aesthetic judgment (I think This produces prettier results than That).
What are some ways to tell when a question is too subjective to really be answerable by a community of artists and crafters?
In addition, what suggestions or guidelines can we make to help turn a very opinion-based question into something that's more answerable and aligned with StackExchange principles?