It's extremely subjective and situational, but there are a lot of metrics that one could apply (though there's not necessarily an objective way to measure them), and if a language scores low on everything, one might call it "bad". But which metrics are important to you is going to vary quite a lot. Here are some I can think of:
I'm probably forgetting some. But in general, if something scores low on all these (or at least the ones you care about), then you might be justified in calling it "bad". But then what you care about might not be what the language authors care about.
There are also deliberately "bad" languages like Brainfu*k and Intercal. But maybe they're good for their intended use, which might make them not really bad.
Great post! Looking at your list it's easy to see how some may favor friendliness and strong community culture when they're just starting out with a language or programming in general.
On the other hand, more seasoned developers might bash that same language for its "syntactic sugar" and its slow compile time.
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