When it's more like voyeurism.
When it kills the cat.
when you're paying for NASA's Mars exploration
a lot of Mars bars as well
when it kills the cat
When the Cat dies! Never as long as it does not hurt anyone.
curiosity by its self never does its action that hurts others and action that helps them also!
When you or someone else gets hurt in any way.
When it causes you to open other people's mail...or their drawers.
Ok, maybe never was a bit of an exaggeration, but there is definitely a lot to be curious about :)
Not unless you're a cat...
When you cannot handle it.
When one pokes his/her nose in other people's business to such an extent that they begin to tell lies and gossip.