The FAQ says it all. It's also discussed in a blog post. Constructive subjective questions meet most, if not all, of the criteria for good subjective questions. If there is extended discussion, then there are many equally valid answers or the question might be pushing other questions off the site where they won't get answered as quickly.

What kind of questions should I not ask here?

You should only ask practical, answerable questions based on actual problems that you face. Chatty, open-ended questions diminish the usefulness of our site and push other questions off the front page. To prevent your question from being flagged and possibly removed, avoid asking subjective questions where …

• every answer is equally valid: “What’s your favorite ______?”
• your answer is provided along with the question, and you expect more answers: “I use ______ for ______, what do you use?”
• there is no actual problem to be solved: “I’m curious if other people feel like I do.” we are being asked an open-ended, hypothetical question: “What if ______ happened?”
• it is a rant disguised as a question: “______ sucks, am I right?”

If your motivation for asking the question is “I would like to participate in a discussion about ______”, then you should not be asking here. If your motivation is “I would like others to explain ______ to me”, then you are probably OK.

Extended discussions are more suitable for a forum or a chat room, not a question and answer site. You can make your own chat rooms on Stack Exchange sites for particular discussions, and most site (including Programmers) has a general catch-all chat room. These chat rooms are archived and can be linked to as references in answers to appropriate questions, from your blog, or on your choice of social network (which might also be an appropriate place for an extended discussion).

The FAQ says it all. It's also discussed in a blog post. Constructive subjective questions meet most, if not all, of the criteria for good subjective questions. If there is extended discussion, then there are many equally valid answers or the question might be pushing other questions off the site where they won't get answered as quickly.

What kind of questions should I not ask here?

You should only ask practical, answerable questions based on actual problems that you face. Chatty, open-ended questions diminish the usefulness of our site and push other questions off the front page. To prevent your question from being flagged and possibly removed, avoid asking subjective questions where …

• every answer is equally valid: “What’s your favorite ______?”
• your answer is provided along with the question, and you expect more answers: “I use ______ for ______, what do you use?”
• there is no actual problem to be solved: “I’m curious if other people feel like I do.” we are being asked an open-ended, hypothetical question: “What if ______ happened?”
• it is a rant disguised as a question: “______ sucks, am I right?”

If your motivation for asking the question is “I would like to participate in a discussion about ______”, then you should not be asking here. If your motivation is “I would like others to explain ______ to me”, then you are probably OK.

Extended discussions are more suitable for a forum or a chat room, not a question and answer site. You can make your own chat rooms on Stack Exchange sites for particular discussions, and most site (including Programmers) has a general catch-all chat room. These chat rooms are archived and can be linked to as references in answers to appropriate questions, from your blog, or on your choice of social network (which might also be an appropriate place for an extended discussion).