These questions were voted down ... because they were too broad or subjective.
But shouldn't we have some off-topic questions like this to show new users what they shouldn't do?
No. Common mistake. [Closed as subjective] examples don't tell you anything about the site.
Don't confuse the reasons to close a question with whether a question is on- or off- topic. Those off-topic questions are supposed to tell you what the site is not about... What questions would be [closed as off-topic].
Most people are "getting" this because the voting results have been pretty darn good. But on occasion, I still see some confusion between "great off-topic example" and simply a bad question. I am working on a blog post to help clarify, but let me see how much I can emphasize this point:
The fact that a sample question is too broad or too subjective is a terrible, terrible, terrible reason to vote the question as a "great off-topic example."
It does nothing to help you define your subject space, and even worse, it will likely mislead your audience. Let me illustrate with an example (I am totally making this up):
Topic: Coffee ... for professional drinkers and grinders of coffee.
(supposedly) great off-topic example: "Which is better, cappuccino or espresso?"
Obviously, this question would be [closed as subjective]... but is it an EXEMPLARY off-topic question? Let's pretend it was voted as the perfect off-topic question and the site gets created. The coffee enthusiast sees your site and is going to decide "Whoa! That's my kinda site!"... or they aren't. They see the FAQ which now looks something like this:
Welcome to CoffeeOverflow. Blah, blah, blah.
This site is about:
- How do I roast my own coffee beans?
- What is the difference between a blade grinder and a burr grinder?
- How finely should I grind for moka?
This site is NOT about:
- Can coffee cause you to gain weight?
- At which stores can I get Yemeni coffee beans?
- Which is better cappuccino or espresso? ←—————— WTF?
For some crazy reason, this coffee site isn't about cappuccino and espresso. Buh-bye!
The off-topic questions are supposed to tell you what questions would be [closed as off-topic].
Subjective or overly broad questions may well be [closed as subjective] but that has absolutely nothing to do with defining the scope of your site!... that's an issue of moderation policy and nobody cares. Bad question.
Let me finish with some examples of some awesome off-topic questions:
For a site about "The Business of Stand-Up Comedy," you just know someone is going show up telling jokes.
"So a priest, a rabbi and a duck sit down at a bar..." [a must-have off-topic question]
A site for "Professional Chefs," you just know some Internet drive-by is going to treat the site like one of the 10,000 other recipe exchanges out there.
"What is a good recipe for brownies?" [dead, spot-on awesome off-topic question]
Superuser.com, a site about computer hardware and software
"How do you merge your World of Warcraft and Battle.net accounts?" [100% awesome. Tells people there is an explicit prohibition against video game questions]
- A site for "Digital Photography"
"Where's a good place to buy a Canon EOS-1D Mark IV
I think most every site should have have a good off-topic question which explicitly prohibits general shopping advice.